Questions rise about seeding for ocean C02 sequestration – Argonne National Laboratory
LEMONT, Ill – A new study on the feeding habits of ocean microbes calls into question the potential use of algal blooms to trap carbon dioxide and offset rising global levels.
These blooms contain iron-eating microscopic phytoplankton that absorb C02 from the air through the process of photosynthesis and provide nutrients for marine life. But one type of phytoplankton, a diatom, is using more iron that it needs for photosynthesis and storing the extra in its silica skeletons and shells, according to an X-ray analysis of phytoplankton conducted at the U.S. Department of Energy’s Argonne National Laboratory. This reduces the amount of iron left over to support the carbon-eating plankton.
“Just like someone walking through a buffet line who takes the last two pieces of cake, even though they know they’ll only eat one, they’re hogging the food,” said Ellery Ingall, a professor at the Georgia Institute of Technology and co-lead author on this result. “Everyone else in line gets nothing; the person’s decision affects these other people.”
Because of this iron-hogging behavior, the process of adding iron to surface water – called iron fertilization or iron seeding – may have only a short-lived environmental benefit. And, the process may actually reduce over the long-term how much C02 the ocean can trap.
Rather than feed the growth of extra plankton, triggering algal blooms, the iron fertilization may instead stimulate the gluttonous diatoms to take up even more iron to build larger shells. When the shells get large enough, they sink to the ocean floor, sequestering the iron and starving off the diatom’s plankton peers.
Over time, this reduction in the amount of iron in surface waters could trigger the growth of microbial populations that require less iron for nutrients, reducing the amount of phytoplankton blooms available to take in C02 and to feed marine life.
While scientists have known for a long time that phytoplankton use iron to fuel the process of photosynthesis, there are gaps in their understanding of how this iron cycling process works. Those gaps led scientists to miss how large an amount of iron was getting trapped in those sinking skeletons and removed permanently from the food chain. X-ray studies at the Advanced Photon Source at Argonne gave scientists a way to measure the ratio of iron and silica in the plankton and surface water.
“Being able to use X-rays and see the element content of individual microscopic phytoplankton has completely altered our perspective on how these organisms use iron and how that could affect C02 levels,” Ingall said.
In the paper “Role of biogenic silica in the removal of iron from the Antarctic seas” published June 10 in the journal Nature Communications, scientists conservatively estimate that 2.5 milligrams of iron annually is removed from every square meter of surface water in the Ross Sea and sequestered in silica skeletons on the ocean floor. This is roughly equivalent to the total amount of iron deposited annually into the Ross Sea surface through snow melt, dust and upwelling of seawater.
The same process may be occurring in the Southern Ocean and having a greater impact there, because this region dictates the nutrient mix for the rest of the world’s oceans through migratory current patterns.
More study is needed to know just how much iron is used to make the silica skeletons and how much gets trapped on the ocean floor, the researchers said.
“This gap in our knowledge, combined with renewed interest in iron fertilization as an approach to the current climate crisis, makes it crucial that we have an improved understanding of iron cycling in marine systems,” Ingall said.
Measurements of iron and silicon content in silica from living phytoplankton collected in the coastal seas of West Antarctica was derived through X-ray analysis on beamlines 2-ID-D and 2-ID-E at the Advanced Photon Source using microscopy and fluorescence techniques. High-resolution imaging, chemical identification and the ability to focus X-rays on an ultra small area of about 200 by 200 nanometers were key to this analysis. For comparison, it would take 500 samples of this size to fit across the width of a single human hair.
The work was supported by the National Science Foundation and the Swedish Antarctic Research Programme. The U.S. Department of Energy’s Office of Basic Energy Sciences supported use of the APS.
The research was conducted by Ingall, Julia Diaz, Amelia Longo and Michelle Oakes from the Georgia Institute of Technology; Lydia Finney, Stefan Vogt and Barry Lai from the Advanced Photon Source; Patricia Yager from the University of Georgia; Benjamin Twining from the Bigelow Laboratory for Ocean Sciences; and Jay Brandes from the Woods Hole Oceanographic Institution.
The Goergia Institute of Technology news release can be viewed on its website.
The Advanced Photon Source at Argonne National Laboratory is one of five national synchrotron radiation light sources supported by the U.S. Department of Energy’s Office of Science to carry out applied and basic research to understand, predict, and ultimately control matter and energy at the electronic, atomic, and molecular levels, provide the foundations for new energy technologies, and support DOE missions in energy, environment, and national security. To learn more about the Office of Science X-ray user facilities, visit the Office of Science website.
Argonne National Laboratory seeks solutions to pressing national problems in science and technology. The nation’s first national laboratory, Argonne conducts leading-edge basic and applied scientific research in virtually every scientific discipline. Argonne researchers work closely with researchers from hundreds of companies, universities, and federal, state and municipal agencies to help them solve their specific problems, advance America’s scientific leadership and prepare the nation for a better future. With employees from more than 60 nations, Argonne is managed by UChicago Argonne, LLC for the U.S. Department of Energy’s Office of Science.
– See more at: http://www.anl.gov/articles/questions-rise-about-seeding-ocean-c02-sequestration#sthash.RNoUhS9O.dpuf
Old ground.
Hoser says:
February 2, 2011 at 9:01 am
Is 25 billion tons of carbon per year dropping to the ocean floor without fertilization insignificant? And how much iron do we need to drop over 361 million km^2 to boost that amount – every year?
You need to provide 4nM iron (1). Assuming 1 m depth for each m^2 of area, you need 223 mg/m^2, or 223 kg/km^2. To fertilize the entire ocean requires 81 million tons of Fe, or 219 million tons of FeSO4. At 2840 kg/m^3, you need 77 million m^3 of iron sulfate. The iron dissipates within 3 days of last application. How many times per year do we want to do this?
Coale, et al. (1) recognize the challenge of scaling up their experiments. “[A] mesoscale enrighment experiment in these Southern Ocean waters poses a tantalizaing, yet formidable, challenge.”
Iron fertilization of every square kilometer of ocean is not possible or necessary, however, it certainly would be necessary to deliver iron monthly or more frequently to the selected ocean regions to have any lasting effect. Furthermore, to achieve any significant impact on atmospheric CO2 concentrations, a majority of ocean surface area in the most productive regions would need to be treated.
It is amusing to see what happens when laboratory-scale thinking has to meet the reality of the real world.
And what’s your carbon footprint to deliver all that iron?
1) http://www.unioviedo.es/marioquevedo/eco3/AGN_coale_et_al_96_nature.pdf
So let’s see if I understand this correctly. We have a shortage of iron in the oceans right now. Why else would we want to seed some. Those critters we want to feed are still alive even though those other critters we don’t like grabbed all of the iron cookies off the table? Green cheese.
Wayne Delbeke says:
June 12, 2013 at 9:04 pm
“Crispin in Waterloo – yes it was all about money.
The Haida Quaii tried “dusting” the ocean with iron last fall much to the horror of many:
http://www.timescolonist.com/business/haida-gwaii-we-have-created-life-out-there-1.2010
”
Interesting. All the screaming by the Guardian and by the UN etc. means, they don’t want anyone to meddle with their scam, it’s THEIR scam and they will decide how to pillage the populous and where to hide the carbon credit dollars.
The best line is
” Using the ocean as a carbon sink can cause ocean acidification”
which shows that University of Victoria climate scientist Andrew Weaver has no knowledge about what photosynthesis actually is.
All this talk about iron fertilisation only makes sense as long as it is known for certain that iron is a limiting factor. Even if it is, by flooding a cell’s iron requirement, you simply hit the next limit. It may be cobalt or zinc. Maybe the present cobalt requirement trumps the iron one, so no amount of iron thrown in will have any effect. One can’t know that without doing a meticulous research of that particular site and its inhabitants. For each type of cell, there are hundreds of factors limiting its growth, and then there are interactions between the species, making the situation all but inscrutable.
We are again trying to interfere in a system we little understand. This will lead to more problems that it is committed to solve.
It is not as if we are on a planet short of iron either, and this situation must have happened before and the seas still live, the planet is still here.
We have to somehow bring a more rapid end to this dangerous foolishness. The ocean and its inhabitants have a long relationship in cyclic balance and unbelievably hare-brained schemes involving billions of tons of anything added to the sea WILL have unintended consequences- we don’t need scientific studies to tell us this. Fortunately iron is not cheap to produce, transport and spread so we are saved from any significant scale projects of this kind by the Luddites in universities and scientific institutions where these ideas come from. What a sight to behold – billions of tonnes of iron ore strip-mined and transported by unit trains and ships (probably we will produce the CO2 we need in the process!) without an environmental protest!! I’m in the mining industry and I find this scary.
Why is it always the biologists who on the one hand are saving the ‘snail darter’ from a hydro dam
http://en.wikipedia.org/wiki/Snail_darter_controversy
and on the other coming up with these ridiculous schemes? This is sufficient for a mass psychosis diagnosis.
Gene Selkov says:
June 13, 2013 at 3:09 am
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Gene, this is more grade school science project…..
….they just discovered what causes red tides
snark
..but you’re exactly right