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Jeff Schmaltz, MODIS Rapid Response Team at NASA GSFC
The plume of ash and steam rising from the Eyjafjallajokull volcano reached 17,000 to 20,000 feet (5 to 6 kilometers) into the atmosphere on May 10, 2010, when the Moderate Resolution Imaging Spectroradiometer on NASA's Aqua satellite captured this image.
By Charles Q. Choi
LiveScience
The explosive volcanic eruption Iceland saw in 2010 may have disrupted life in the air above Europe, but it apparently enriched life in the Atlantic Ocean, researchers say.
After nearly two centuries of dormancy, the volcano Eyjafjallajökull (AYA-feeyapla-yurkul) erupted many times over the course of 10 weeks three years ago. These outbursts spewed a giant plume of ash that spread unusually far and stayed for an oddly long time in the atmosphere, forcing widespread flight cancellations for days.
Serendipitously, marine biogeochemist Eric Achterberg at the University of Southampton in England and his colleagues were taking part in a series of research cruises in the Iceland Basin region of the North Atlantic Ocean both during and after the eruption. These three cruises allowed the researchers to measure iron concentrations at the ocean's surface before, during and after the eruption in areas directly influenced by the plume of iron-rich ash.
"This was really the first time scientists have been under a volcanic plume at sea and could really look at the immediate effects of the ash falling into the ocean," Achterberg said. "That was really exciting, doing something that's never been done before." [Gallery: Iceland Volcano's Fiery Sunsets]
Ocean bloom
Iron is key to ocean life, helping spur the growth of single-celled organisms known as phytoplankton. Like plants, these organisms convert sunlight to chemical energy via photosynthesis and serve as the base of the food chain. In about a third of the global ocean, a scarcity of iron limits the abundance of life, so ash supplying this metal could spur booms in biological activity.
Beneath the plume, the scientists found that peak dissolved iron levels were up to about 20 to 45 times higher after the plume than they had been before the ash came along. A model of ash dispersal rate that the researchers developed, along with measurements of iron dissolution, suggest that up to 220,000 square miles (570,000 square kilometers) of North Atlantic waters might have been seeded with up to about 100 metric tons of iron.
The researchers also saw that after the eruption, levels of another nutrient, nitrate, were nearly completely depleted in the central Iceland Basin. That finding suggests that when volcanic iron fertilized the waters, the resulting phytoplankton bloom sucked up other nutrients as well.
Since phytoplankton use carbon dioxide just like plants do, volcanic ash falling on the ocean could reduce levels of the greenhouse gas in the atmosphere. However, the team estimated that the plume from Eyjafjallajökull only triggered a 10 to 20 percent rise in carbon dioxide uptake by phytoplankton in the Iceland Basin compared to other years. In order for volcanic iron to have larger effects on the atmosphere, phytoplankton must really flourish. For that to happen, the researchers suggest, ash emissions have to be much larger and longer in duration and must occur over a region high in nitrate.
Blow to geoengineering
The relatively modest effects that this volcanic iron apparently had on atmospheric carbon dioxide levels strike another blow against so-called geoengineering schemes that aim to reduce levels of greenhouse gases by adding large amounts of iron to the seas.
"I'm not an advocate of dumping into the ocean to remove atmospheric carbon dioxide," Achterberg said. "It's not a very efficient process. You'd need so much iron to remove the man-made carbon dioxide emitted at the moment that it wouldn't be worth it."
In the future, researchers could investigate the effects of volcanic ash on the Southern Ocean, which is relatively rich in nitrate. "There, you might see more of an effect when you add extra iron via ash," Achterberg said. "However, you'd have to be lucky to be at sea when a volcano erupted there. Our cruise was scheduled three years in advance, and it was just pure luck we were in the Iceland Basin when Eyjafjallajökull erupted."
The scientists detailed their findings online March 14 in the journal Geophysical Research Letters.
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First we need to remember some basic physics. The amount of dissolved gases (like carbon dioxide) that a liquid (the oceans) had absorb and hold varies with temperature and pressure. A cold liquid can hold more than a warm liquid.
That's why if you were to take two identical sodas, one cold and one warm and shake both of them then open, the warm soda will spew more than the cold one. The warm ocean can't hold as much CO2.
So it isn't the amount of CO2 in the air that regulates how much CO2 is in the ocean. It is the temperature of the ocean that regulates how much CO2 is in the air.
That's why all this talk about ocean acidification is flawed. A warmer ocean is physically unable to hold as much CO2 as a cold ocean. Of course the entire description 'acidification' is inaccurate. The pH has to drop below 7.0 (neutral) for anything to be acidic. Just as you can't call a reduced acid orange juice basic or alkaline you can't say that ocean water with a pH of 8.0 is more acid than one of 8.2. You have to say less basic or less alkaline.
Even if someone disagrees with what I wrote they would have to agree that using proper, correct terminology is the right thing to do.
You wouldn't look at a gray cat and call it more black or less white. That's why the 'acidification' term needs to go.
It's a continuum. More acidic and less alkaline are the same thing. They are relative terms. It doesn't have to be relative to neutral.
Partly right on the issue of how much gas an aqueous solution can hold. That is indeed dependant on temperature and pressure. However, the ocean does not only hold CO2 as a gas. CO2 in aqueous solutions is also converted into various forms of carbonate (CO3). The increased levels of CO2 increases the amount of carbonic acid (H2CO3) and sodium bicarbonate (NaHCO3) in the water relative to the sodium carbonate (Na2CO3). And as the CO2 levels in the air increase, so do the levels of carbonic acid. Thus the ocean becomes acidified. This is measurable and has been verified in areas where there are natural seeps, and where the water is significantly more acidic than in surrounding waters.
It is very important water chemistry, as animals such as corals and shellfish depend on alkaline waters to secrete calcium carbonate (Ca2CO3). The more acidic the water, the harder they have to work to secrete the carbonate, and the less viable they are. In naturally acidic waters, there are no corals and very few shellfish, and the ones that are there are stunted.
And jock is right - pH is a continuous scale indicating the relative ratios of acidic ions to alkaline ions: 0 is extremely acidic, 14 is extremely alkaline, and everything in between is relative to those extremes. So yes, a pH of 8.0 is more acidic than a pH of 8.2, and likewise a pH of 4.2 is more alkaline than a pH of 4.0.
The oceans are absorbing several gigatons of CO2 each year, about half of what we've emitted since the 1880's, and around one fourth of what we emit now. (Recent plant growth has taken up some of the slack, but that's unlikely to continue much longer.) That oceanic increase is because of increased atmospheric CO2, not because the oceans are cooling.
But you are partially right. As the oceans warm, they will at some point begin to give off CO2 instead of absorbing it, which will significantly accelerate global warming as a positive feedback. That will happen in anywhere from a bit less than 200 years to 600 or more years.
The idea is to get phytoplankton in the ocean to grow and multiply again, so they can convert dissolved CO2 back into O2. Fertilization of the oceanic surface water is a very good way to promote this, and I personally think this idea of using non-acidic lava (either old lava flows or new lava) to supply the necessary minerals for this fertilization is potentially a wonderful idea! I have already proposed bringing back either corporate or national fleets of ultra modern (concrete?) sailing ships to distribute this fertilizer throughout our oceans, with the idea of earning valuable green credits along the way. If I were POTUS, in would definitely incorporate this approach into any list of possible solutions for the future, when it comes to solving global warming. - Rick Carter
Correction: - "If I were POTUS, I would definitely incorporate this approach into any future list of possible solutions when it comes to solving global warming." - Rick Carter
(I also proposed incorporating these minerals into some kind of biologically safe foam, which the wind and the ocean currents can then further distribute, which slowly dissolves (or gets degraded by the sun) on the surface of the ocean as it gradually gets carried about.) - RC
Just curious. Has anyone thought of feeding seagulls (or some other form of oceanic life) with food which then fertilizes the ocean waters with their poopings? Why not engage Mother Nature in this way, when it comes to saving Mother Earth? - RC