Nature eifex report

[Andrew Lockley]

Personally I find the claims of 13000 tonnes to 1 atom of iron somewhat difficult to comprehend!

A

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Nature doi:10.1038/nature.2012.11028

Dumping iron at sea does sink carbon

Geoengineering hopes revived as study of iron-fertilized algal blooms shows they deposit carbon in the deep ocean when they die.
Quirin Schiermeier
18 July 2012

In the search for methods to limit global warming, it seems that stimulating the growth of algae in the oceans might be an efficient way of removing excess carbon dioxide from the atmosphere after all.

Despite other studies suggesting that this approach was ineffective, a recent analysis of an ocean-fertilization experiment eight years ago in the Southern Ocean indicates that encouraging algal blooms to grow can soak up carbon that is then deposited in the deep ocean as the algae die.

In February 2004, researchers involved in the European Iron Fertilization Experiment (EIFEX) fertilized 167 square kilometres of the Southern Ocean with several tonnes of iron sulphate. For 37 days, the team on board the German research vessel Polarstern monitored the bloom and demise of single-cell algae (phytoplankton) in the iron-limited but otherwise nutrient-rich ocean region.

Each atom of added iron pulled at least 13,000 atoms of carbon out of the atmosphere by encouraging algal growth which, through photosynthesis, captures carbon. In a paper in Nature today, the team reports that much of the captured carbon was transported to the deep ocean, where it will remain sequestered for centuries1 — a 'carbon sink'.

“At least half of the bloom was exported to depths greater than 1,000 metres,” says Victor Smetacek, a marine biologist at the Alfred Wegener Institute for Polar and Marine Research in Bremerhaven, Germany, who led the study.

The team used a turbidity meter — a device that measures the degree to which water becomes less transparent owing to the presence of suspended particles — to establish the amount of biomass, such as dead algae, that rained down the water column towards the sea floor. Samples collected outside the experimental area showed substantially less carbon being deposited in the deep ocean.
Iron findings

The EIFEX results back up a hypothesis by the late oceanographer John Martin, who first reported in 1988 that iron deficiency limits phytoplankton growth in parts of the subarctic Pacific Ocean2. Martin later proposed that vast quantities of iron-rich dust from dry and sparsely vegetated continental regions may have led to enhanced ocean productivity in the past, thus contributing to the drawdown of atmospheric carbon dioxide during glacial climates3 — an idea given more weight by the EIFEX findings.

Some advocates of geoengineering think that this cooling mechanism might help to mitigate present-day climate change. However, the idea of deliberately stimulating plankton growth on a large scale is highly controversial. After noting that there were gaps in the scientific knowledge about this approach, the parties to the London Convention — the international treaty governing ocean dumping — agreed in 2007 that ‘commercial’ ocean fertilization is not justified (see 'Convention discourages ocean fertilization').

The finding that ocean fertilization does work, although promising, is not enough to soothe concerns over potentially harmful side effects on ocean chemistry and marine ecosystems, says Smetacek. Some scientists fear that massive ocean fertilization might produce toxic algal blooms or deplete oxygen levels in the middle of the water column. Given the controversy over another similar experiment (see 'Ocean fertilization experiment draws fire'), which critics said should not have been approved in the first place, the Alfred Wegener Institute will not conduct any further artificial ocean-fertilization studies, according to Smetacek.

“We just don’t know what might happen to species composition and so forth if you were to continuously add iron to the sea,” says Smetacek. “These issues can only be addressed by more experiments including longer-term studies of natural blooms that occur around some Antarctic islands.”

But some experts argue that artificial ocean-fertilization studies should not be abandoned altogether. “We are nowhere near the point of recommending ocean fertilization as a geoengineering tool,” says Ken Buesseler, a geochemist at the Woods Hole Oceanographic Institution in Massachusetts. “But just because we don't know all the answers, we shouldn't say no to further research.”

[Mick West]

It says 13,000 atoms, not tonnes:

"Each atom of added iron pulled at least 13,000 atoms of carbon out of the atmosphere by encouraging algal growth which, through photosynthesis, captures carbon."

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[Rau, Greg]

So 1 tone of added Fe captures 2786 tones of C or 10,214 tones of CO2 (?) Then the issue is how much of this stays in the ocean for how long.  I'll have to read the fine print.

-Greg

[Ken Caldeira]

Recall that this fertilization is using up macronutrients such as N and P that may have been used elsewhere at a later date. 

So, to some extent, iron fertilization concentrates productivity in space and in time.  

An important question is: how much of the P that was in the fertilized water would have been mixed downward as phosphate and how much of it would have been transported downward biologically at a later date somewhere else. 

It is only the fract of P that would not have been used biologically somewhere else at a later date that represents the increase in biological export.

On top of this, there are additional questions of how the C/P ratio and remineralization depth of this carbon that would have been naturally exported differs from the C/P ratio and remineralization depth of the carbon that was exported in the experiment.

So, two difficulties in analyzing these results are

(1) Determining effects that are distal in space and time associated with the local (in space and time) consumption of macronutrients

(1) establishing the counterfactual baseline that could be subtracted from the experimental case to determine the delta, taking into consideration effects that are distal in space and time (see previous point)

[Bhaskar M V]

Ken

You are right to a certain extent when you say -

"So, to some extent, iron fertilization concentrates productivity in space and in time."

However the facts are as follows -

Human action has increased the amount of N and P in water.

The Nitrogen (and Phosphorus) cycles have been both speeded up and increased in volume.

About 100 million tons of urea is manufactured and used as fertilizer in agriculture, most of this is made by the Haber-Bosch process of capturing Nitrogen from atmosphere and converting it into ammonia and then into urea.

Thus we are adding more N into water.

Phosphate fertilizer is made by mining rock phosphate and converting this into phosphoric acid and then into super phosphate, etc.

Thus insoluble rock phosphate and N2 gas in atmosphere are being converted into soluble N and P in water.

Another way to calculate the increase in N and P due to human action is to compute the average food intake of people and the N and P content of this and multiply with the population. 

If we consume about 1 kg of food (wet weight) per day, this may contain say 50 mg of N and 10 mg of P. Multiply with the population of 1 billion 200 year ago, 7 billion today and projected population of 9 billion by 2050 and you can get the total increase in N and P in food and sewage input into lakes, rivers and oceans. I am not attempting to quantify the actual numbers, since there are too many variables and averages, the concept is adequate for the present.

What is the consequence of this?

1000s of eutrophic lakes and 500+ dead zones in the coastal waters.

This is the N and P that will be used up to sequester carbon when oceans are fertilized with iron. 

So there is no need to worry about depletion of macro nutrients in oceans.

:) Once we run out of oil, we can use the defunct Oil tankers to transport sewage to Southern Ocean to provide the macro nutrients required. Prof John Martin's recommended dose of half a tanker load of iron can be matched with a 100 tanker loads of sewage. :)

I guess physicists always get lost in space and time.

regards

Bhaskar

[O Morton]

The reported ratio of C:Fe for IEFEX is >10,000:1. The redfield C:P ration is about 100:1. So you'd need your 100 tankers to be carrying pure phosphate, not sewage, no? 

Bhaskar

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[Mike MacCracken]

Bhaskar--

With respect to your message, I would very much like to see the evidence for the oxygen content ever being as high as 35% when life was present as fire would have run rampant (and since lightning would have been needed to provide the nitrate source, there would not have been a lack of a natural match). If that supposedly high oxygen content is what underpins your assurance that there are plenty of nutrients, then that conclusion would also seem to come into question.

It really is not so much whether the full ocean waters contain adequate nutrients, but how much (or few) make it up to the upper ocean and at what rate. With warming of surface waters likely to tend to stabilize the oceans (so reducing the bottom water formation that presumably forces colder, nutrient rich waters up), it would seem to me much more likely that the nutrient supply of the upper ocean would be headed down instead of up. Now, Kerry Emanuel has suggested that the restraint on the thermohaline circulation may not be the problem of getting cold waters to sink, but of getting them to come back up, and that tropical cyclones likely play an important role in this. While the number of tropical cyclones is projected to decrease, what the net effect (fewer tropical cyclones, perhaps more powerful, more stable ocean, etc.) on drawing up deeper colder waters remains, as I understand it, a bit murky, so it seems to me postulating a lot more nutrients reaching the surface layer is not at all well-established, and how the marine biological pump would work in the face of ocean acidification is also unclear—the notion of a great increase seems to me quite premature, at best.

Mike MacCracken


On 7/23/12 7:31 AM, "M V Bhaskar" <bhaska...@gmail.com> wrote:

Morton

Iron fertilization is planned to be used in HNLCs, i.e., areas that have high nutrient levels year after year.
So it appears that there is a abundance of nutrients in the oceans.

In the past the CO2 levels of atmosphere and oceans were lower due to natural factors and diatom growth higher, so nutrients to support this were available.

O2 levels of atmosphere is today ~ 21 %, peak was ~ 35%.
So nutrients to support more than 50% higher photosynthesis was available at that point in time.

P is available only as a solid or dissolved in water, never as gas.
N may exit lakes and oceans as N2 gas but not P.

So P to support much higher level of photosynthesis was and is available on land or in water, if it has to be transported it can be done - whether 100 tankers are required or 1000 tankers are required will be known only if we experiment.

Excess carbon in the atmosphere is about 200 billion tons - 390 ppm - 280 ppm.
At 100 : 1, total P requires is less than 1 billion tons.

Annual carbon emissions are 10 billion tons of C, P required is about 50 million tons.

Global Rock Phosphate production is 256 million tons.
Rock Phosphate reserves in Western Sahara alone are about 50 Billion tons.
http://minerals.usgs.gov/minerals/pubs/commodity/phosphate_rock/mcs-2012-phosp.pdf

There seems to be no danger of running out of phosphorus.

Before you ask how many tankers are required, please read -

African dust leads to large toxic algal bloom
http://eospso.gsfc.nasa.gov/ftp_docs/African_Dust.pdf

"Each year, several hundred million tons of African dust are transported westward over the Atlantic
to the Caribbean, Gulf of Mexico, Central America, and South America."

"Plant-like bacteria use the iron to set the stage for red tide, a toxic algal bloom. When iron levels
go up, these bacteria, called Trichodesmium, process the iron and release nitrogen in the water,
converting it to a form usable by other marine life. The increased nitrogen in the water makes the
Gulf of Mexico a friendlier environment for toxic algae. The image on the left shows a red tide
event that was seen by the SeaWiFS sensor on August 26, 2001. A huge bloom of toxic red algae,
called Karenia brevis (K. brevis), appears on the true-color image as a black area hugging the
Florida Gulf Coast from the Keys to Tampa Bay."

The dust contains P, Si and Fe.
N is fixed from atmosphere by cyanobacteria - Trichodesmium.

The key is to ensure bloom of useful algae and not harmful algae.
We have the key. We can prevent this dust from causing toxic algal bloom by a very scientific fertilization to cause a controlled bloom of diatoms instead of dinoflagellates (red tides).

regards

Bhaskar

On Saturday, 21 July 2012 17:31:15 UTC+5:30, O Morton  wrote:

[Bhaskar M V]

Mike

Historical oxygen levels are a question of fact.

No logic is involved.

Wikipedia

http://en.wikipedia.org/wiki/Atmosphere_of_Earth 

A good graph of O2 levels

http://www.nap.edu/openbook/0309100615/gifmid/30.gif 

http://www.pnas.org/content/96/20/10955.full 

Oxygen and Paleofires.

The level of atmospheric oxygen cannot rise indefinitely unless the frequency of forest fires becomes so excessive that plant life cannot persist. This has been pointed out by Watson et al. (27), who emphasize that fires serve as strong negative feedback against excessive O₂ variation. Conversely, O₂ cannot have dropped to such low values over Phanerozoic time that fires became impossible. Fossil charcoal, as evidence of paleofires, has been found for all times that trees have populated the land, and the lower limit for the production of charcoal has been estimated to be at about 13% O₂ (28). By contrast, the upper limit for O₂ is in dispute. On the basis of experiments on the ignition of paper strips at different oxygen levels and fuel moisture contents, Watson et al. (27) concluded that past levels of atmospheric O₂ could never have risen above 25%. However, consideration of actual forest fires and the response of ecological disturbance to fires led Robinson (29) to conclude that greater O₂ variation might occur and that, at any rate, paper is not a good surrogate for the biosphere. In fact, Robinson states paleobotanical evidence for a higher frequency of fire-resistant plants during the Permo-Carboniferous, supporting the idea of distinctly higher O₂levels at that time."

Apparently there is evidence of more fires, and more fire resistant plants.

Fires would only impact terrestrial life, since more than 50% of life is in oceans the issue of fires is quite irrelevant.

While discussing the past, facts should always prevail over logic.

O2 level today is 20.95%.

CO2 level is 0.039% - desirable level is 0.028%.

So required increase in O2 level is about 0.01% i.e., from 20.95 % to ~ 20.96 %.

In fact the issue may not be an overall increase in photosynthesis at all.

If share of diatoms increases and share of other phytoplankton decreases correspondingly the desired result can be achieved.

Diatoms account for about 40 to 50% of primary production in oceans, if this is increased to 50 to 60% with corresponding reduction in share of other phytoplankton, macro algae, weeds, etc., it would be adequate.

Since diatoms and other phytoplankton consume similar amounts of nutrients - N and P, there is no need to even discuss whether nutrient availability is adequate or not.

If farmers grew weeds instead of grass, we would starve.

In oceans too we should grow grass (Diatoms) instead of weeds (Cyanobacteria and Dinoflagellates).

regards

Bhaskar

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[Mike MacCracken]

Bhaskar--

Pardon me, but I don't get the sense from the citations you provided me to justify the finding that the O2 concentration roughly 300M years ago reached 35% raises this bit of information to “a fact”. I’d note also that in the plot you reference that the high O2 level is indicated as having occurred during a time of glaciation, and not warmth.

I would also note that considerable analysis and inference likely went into interpreting the geological evidence that makes up the record. There were no calibrated instruments back then—the inferences usually come from the types of materials being deposited out of lakes and oceans, the pore sizes of fossil plants, etc.--all sorts of proxy data, and so there is clearly analysis, interpretation, and logic involved.

Mike

On 7/23/12 11:27 AM, "Bhaskar M V" <bhaska...@gmail.com> wrote:

Mike

Historical oxygen levels are a question of fact.
No logic is involved.

Wikipedia
http://en.wikipedia.org/wiki/Atmosphere_of_Earth 

A good graph of O2 levels
http://www.nap.edu/openbook/0309100615/gifmid/30.gif 

http://www.pnas.org/content/96/20/10955.full 
Oxygen and Paleofires.

The level of atmospheric oxygen cannot rise indefinitely unless the frequency of forest fires becomes so excessive that plant life cannot persist. This has been pointed out by Watson et al. (27 <http://www.pnas.org/content/96/20/10955.full#ref-27> ), who emphasize that fires serve as strong negative feedback against excessive O2 variation. Conversely, O2 cannot have dropped to such low values over Phanerozoic time that fires became impossible. Fossil charcoal, as evidence of paleofires, has been found for all times that trees have populated the land, and the lower limit for the production of charcoal has been estimated to be at about 13% O2 (28 <http://www.pnas.org/content/96/20/10955.full#ref-28> ). By contrast, the upper limit for O2 is in dispute. On the basis of experiments on the ignition of paper strips at different oxygen levels and fuel moisture contents, Watson et al. (27 <http://www.pnas.org/content/96/20/10955.full#ref-27> ) concluded that past levels of atmospheric O2 could never have risen above 25%. However, consideration of actual forest fires and the response of ecological disturbance to fires led Robinson (29 <http://www.pnas.org/content/96/20/10955.full#ref-29> ) to conclude that greater O2 variation might occur and that, at any rate, paper is not a good surrogate for the biosphere. In fact, Robinson states paleobotanical evidence for a higher frequency of fire-resistant plants during the Permo-Carboniferous, supporting the idea of distinctly higher O2levels at that time."

[Ninad Bondre]

I agree with Mike. Much of what we know about the geologic past is based on the best possible interpretation of fragmentary evidence. While there are contexts in which the past can serve to illuminate the present, I do not think comparisons of Permian and Holocene oxygen concentrations are very useful.

Regarding phosphate-rock availability, the picture is more nuanced than Bhaskar indicates. I explored this in an article early last year (http://www.igbp.net/news/features/features/phosphorushowmuchisenough.5.1b8ae20512db692f2a680002359.html). Western Sahara is purported to have huge phosphate-rock reserves, but some have questioned the actual figures. Also, mining there brings with it geopolitical baggage and is deemed by some to be problematic on humanitarian grounds. The willingness and capacity to explore and mine phosphate rock depends on technological developments, the demand for fertilisers (triggered by the need to grow more food), the market price of phosphorus, etc. It is conceivable that any increase in production will be commensurate with the increased demand for fertilisers, and not with the need to supply nutrients to the surface ocean.

Finally, forrect me if I am mistaken, but 256 million tons is the projected phosphate-rock production for the year 2015, not the figure for today.

Ninad R. Bondre

[Bhaskar M V]

Mike

Your logic was that if O2 was high there would have been huge fires, therefore O2 could not have been that high. 

Perhaps many species became extinct when O2 was high. 

If this is a fact, it is a fact. 

This does not mean O2 could not have been high. 

Many data / evidence is indirect and has to be interpreted, this is not what I called logic.

You said -

" I’d note also that in the plot you reference that the high O2 level is indicated as having occurred during a time of glaciation, and not warmth. "

Exactly what we are trying to achieve, increase O2 and reduce CO2 to cool Earth.

If higher O2 resulted in massive fires, how is it that Earth was cooler?

There are fundamental flaws in your logic.

If there is more oxygen, forests may burn down, but will grow back again.

There could have been mass deaths but not mass extinctions.

All oxygen in atmosphere is from photosynthesis, so there cannot be more oxygen if there were not more plants and if more oxygen and plants are available there would be more oxygen breathing animals.

Ice ages are a fact, why did they occur?

regards

Bhaskar

[Bhaskar M V]

Ninad

The simple point I am trying to make is if we run out of phosphorus ( and / or nitrogen ), we need not worry about anything else.

GHG emissions due to anthropogenic sources are proportionate to N and P usage.

All fuel is purchased and used, just as all food is purchased and consumed.

Fuel causes CO2 emissions and food production consumes and releases N and P.

Thus there is a certain balance between the CO2 emissions and N and P. 

I agree that this may not be a perfect balance in terms of time and space.

If GHGs are released directly by nature, say methane from Arctic ocean then this could be disproportionate to the N and P. 

However, methane is produced by bacteria that grow by decomposing organic matter that contains N and P. The carbon goes into methane, where is the corresponding N and P?

All fossil fuel is derived from fossilised organic matter, the carbon fossilised, where is the corresponding N and P ?

All life on earth is dependent on photosynthesis for past 3500 million years, so the ratio of the inputs for photosynthesis cannot go out of hand.

regards

Bhaskar

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