This is one year old and I think already discussed. The fundamental objective of Iron Fertilization is to grow Diatom Algae, because they are the phytoplankton that will sequester carbon. If other phytoplankton consume the iron, the carbon is likely to be remineralised rapidly.
It is precisely because the Diatoms take Carbon, Silica and Iron to the ocean bed that repeated fertilization is required. So this paper is fundamentally defective and misses the basic reason for Iron Fertilization. 50% of ocean photosynthesis is due to Diatoms, so broadly 50% of the Iron is consumed by them. So when we fertilizer oceans with Iron, we want 50% or even more to be consumed by Diatoms. The fact that Whales help in bringing back to the surface the iron that falls to ocean bed was also posted on this group a few days ago. The report that discussed the Iron content unfortunately did not mention the carbon content or C : Fe ratio of the Whale feces. The C : Fe ratio of Whale feces would be lower than the C : Fe ratio of consumption during photosynthesis ( about 106,000 : 1 ), indicating that the carbon is captured and Iron is recycled by whales. So the faster the iron cycle moves the more will be the carbon captured. If the whales exhaled most of the carbon consumed as CO2 or excreted it via feces, the ratio of O2 : C in the atmosphere and the weight of the Whales would not be so high. Regards Bhaskar On Sunday, 20 July 2014 22:39:15 UTC+5:30, Greg Rau wrote: > > I see this as more of a silica story than a CO2 story. If you do OIF in > areas high in nutrients but depleted both in Fe and Si (e.g., equatorial > upwelling) you presumably still get phytoplankton blooms, just not diatoms. > Then the issue is does this biomass carbon sink or just recycle in the > surface ocean. The effectiveness of this vertical C pump will depend on the > size, shape, and ballast of the phytos doing the C fixing and sinking, as > well as the grazing, respiration, pooping, and sinking efficiency of higher > consumers. > Past performance is not a guarantee of future behavior, results may vary, > void where prohibited, etc. For these reasons and others I'm not a big fan > (yet) of asking open-ocean marine biology to help fix our C problem, there > are just too many pulleys and levers. > Greg > > ------------------------------ > *From:* Mike MacCracken <mmac...@comcast.net <javascript:>> > *To:* Andrew Lockley <andrew....@gmail.com <javascript:>>; Geoengineering > <geoengi...@googlegroups.com <javascript:>> > *Sent:* Sunday, July 20, 2014 7:07 AM > *Subject:* Re: [geo] Iron fertilization could backfire -- ScienceDaily > > What an interesting possible component of a feedback process—if the > climate gets cold and more dust (iron) blows onto the oceans, the diatoms > take up the iron, so less CO2 is taken up and that would allow for more > warming. And vice-versa, if the climate gets warm with lots of vegetation, > dust (iron) to the ocean goes down, starving the diatoms of iron and the > plankton that take up CO2 with less need for iron dominate, pulling CO2 > concentration down. Is this a possible Gaian negative (stabilizing) > feedback process? Is this the real process and DMS cycle just a symbiotic > process along with it—or vice-versa? > > Mike MacCracken > > > On 7/20/14 9:53 AM, "Andrew Lockley" <andrew.lock...@gmail.com> wrote: > > http://www.sciencedaily.com/releases/2013/06/130612144833.htm > > 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 > CO2 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 CO2 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 > CO2 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 CO2 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. > > Journal Reference: > > Ellery D. Ingall, Julia M. Diaz, Amelia F. Longo, Michelle Oakes, Lydia > Finney, Stefan Vogt, Barry Lai, Patricia L. Yager, Benjamin S. Twining, Jay > A. Brandes. Role of biogenic silica in the removal of iron from the > Antarctic seas. Nature Communications, 2013; 4 DOI: 10.1038/ncomms2981 > > -- > You received this message because you are subscribed to the Google Groups > "geoengineering" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to geoengineerin...@googlegroups.com <javascript:>. > To post to this group, send email to geoengi...@googlegroups.com > <javascript:>. > Visit this group at http://groups.google.com/group/geoengineering. > For more options, visit https://groups.google.com/d/optout. > > > -- You received this message because you are subscribed to the Google Groups "geoengineering" group. To unsubscribe from this group and stop receiving emails from it, send an email to geoengineering+unsubscr...@googlegroups.com. To post to this group, send email to geoengineering@googlegroups.com. Visit this group at http://groups.google.com/group/geoengineering. For more options, visit https://groups.google.com/d/optout.
