From Woods Hole Oceanographic Institution – Carbon dioxide pools discovered in Aegean Sea
The location of the second largest volcanic eruption in human history, the waters off Greece’s Santorini are the site of newly discovered opalescent pools forming at 250 meters depth. The interconnected series of meandering, iridescent white pools contain high concentrations of carbon dioxide (CO2) and may hold answers to questions related to deepsea carbon storage as well as provide a means of monitoring the volcano for future eruptions.
“The volcanic eruption at Santorini in 1600 B.C. wiped out the Minoan civilization living along the Aegean Sea,” said Woods Hole Oceanographic Institution (WHOI) scientist Rich Camilli, lead author of a new study published today in the journal Scientific Reports. “Now these never-before-seen pools in the volcano’s crater may help our civilization answer important questions about how carbon dioxide behaves in the ocean.”
Video captured an interconnected series of iridescent subsea pools containing high concentrations of carbon dioxide in the Southern Aegean Sea. Credit:Video by Rich Camilli, Woods Hole Oceanographic Institution
Camilli and his colleagues from the University of Girona, National and Kapodistrian University of Athens, Institut de Physique du Globe de Paris, and Hellenic Centre for Marine Research (HCMR), working in the region in July 2012, used a series of sophisticated underwater exploration vehicles to locate and characterize the pools, which they call the Kallisti Limnes, from ancient Greek for “most beautiful lakes.” A prior volcanic crisis in 2011 had led the researchers to initiate their investigation at a site of known hydrothermal activity within the Santorini caldera. During a preliminary reconnaissance of a large seafloor fault the University of Girona’s autonomous underwater vehicle (AUV) Girona 500 identified subsea layers of water with unusual chemical properties.
Following the AUV survey, the researchers then deployed HCMR’s Thetis human occupied vehicle. The submersible’s crew used robotic onboard chemical sensors to track the faint water column chemical signature up along the caldera wall where they discovered the pools within localized depressions of the caldera wall. Finally, the researchers sent a smaller remotely operated vehicle (ROV), to sample the pools’ hydrothermal fluids.
“We’ve seen pools within the ocean before, but they’ve always been brine pools where dissolved salt released from geologic formations below the seafloor creates the extra density and separates the brine pool from the surrounding seawater,” said Camilli. “In this case, the pools’ increased density isn’t driven by salt – we believe it may be the CO2 itself that makes the water denser and causes it to pool.”
Where is this CO2 coming from? The volcanic complex of Santorini is the most active part of the Hellenic Volcanic Arc. The region is characterized by earthquakes caused by the subduction of the African tectonic plate underneath the Eurasian plate. During subduction, CO2 can be released by magma degassing, or from sedimentary materials such as limestone which undergo alteration while being subjected to enormous pressure and temperature.
The researchers determined that the pools have a very low pH, making them quite acidic, and therefore, devoid of calcifying organisms. But, they believe, silica-based organisms could be the source of the opal in the pool fluids.
Until the discovery of these CO2-dense pools, the assumption has been that when CO2 is released into the ocean, it disperses into the surrounding water. “But what we have here,” says Camilli, “is like a ‘black and tan’ – think Guinness and Bass – where the two fluids actually remain separate” with the denser CO2 water sinking to form the pool.
The discovery has implications for the build up of CO2 in other areas with limited circulation, including the nearby Kolumbo underwater volcano, which is completely enclosed. “Our finding suggests the CO2 may collect in the deepest regions of the crater. It would be interesting to see,” Camilli said, adding it does have implications for carbon capture and storage.
Sub-seafloor storage is gaining acceptance as a means of reducing heat-trapping CO2 in the atmosphere and lessening the acidifying impacts of CO2 in the ocean. But before fully embracing the concept, society needs to understand the risks involved in the event of release.
Temperature sensors installed by the team revealed that the Kallisti Limnes were 5°C above that of surrounding waters. According to co-author Javier Escartin, “this heat is likely the result of hydrothermal fluid circulation within the crust and above a deeper heat source, such as a magma chamber.” These temperatures may provide a useful gauge to study the evolution of the system. Escartin added that “temperature records of hydrothermal fluids can show variations in heat sources at depth such as melt influx to the magma chamber. The pool fluids also respond to variations in pressure, such as tides, and this informs us of the permeability structure of the sub-seafloor.” Changes in the pools’ temperature and chemical signals may thus complement other monitoring techniques as useful indicators of increased or decreased volcanism.
This European – American research collaboration was funded through support from the EU Eurofleets program, Institut de Physique du Globe de Paris, Hellenic Centre for Marine Research, the US National Science Foundation, and NASA’s astrobiology program (ASTEP) which supports autonomous technology development to search for life on other planets. “From a technology perspective, it was a big step forward,” Camilli said.
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Something doesn’t add up here. Notice that the Kallisti Limnes are mentioned to be filled with opalescent water at the beginning of the article and then they allude to this only once more when they mention that silica-based organisms (assumable they mean silica frustule building organisms) may be the source of the opal. The rest of the article and research seems to focus on their “god molecule” CO2.
Carbonic acid is only very slightly denser than water –1,000 kg/m^3 vs 999.97 kg/m^3 — but the water in the Kallisti Limnes was 5 degrees warmer than the surrounding water. Am I missing something here or is CO2 clearly not the reason why the water is dense enough to be trapped in the depressions when it is 5 degrees warmer than the water above it? Could it perhaps have something to do with the opal dissolved in the water? Silicic acid has a density of around 2,200 kg/m^3 and seems much more likely to be the reason for the Kallisti Limnes, but then again it’s so hard to determine anything from press releases when everything is given in qualitative terms.
RWturner
July 17, 2015 at 11:09 am
Excellent point on silicic acid. I noted that it couldn’t be liquid CO2 at 25 bars pressure and ~10C and that hydrothermal fluids have a lot more in them than CO2 including silica which they mention but are vague about the chemistry:
http://wattsupwiththat.com/2015/07/17/one-more-thing-for-greece-to-worry-about-undersea-pools-of-carbon-dioxide/#comment-1987088
individual CO2 molecules don’t have a “state”. They are simply dissolved in water.
Good point RW. It seems likely that microorganism, perhaps fed by silica enriched volcanic exhalation were the main cause of CO2 buildup and warmer water temperatures.
So I’m seeing Telly Savalas, as Ernst Stavro Blofeld, threatening Europe, “Forgive the Greek debt, or we’re going to release all this CO2!”
So, how much CO2 volcanoes and underground fissures really produce?
It’s been 20 years since I am asking this questions, and I am getting only completely unsubstantiated Ferdinand-style answers juggling completely unsubstantiated “Gty” figures. They don’t know, do they?
They probably don’t WANT to know. If the Lake Nyos seep is typical, there’s a lot more CO2 coming from volcanoes than anyone realizes. The Nyiragongo volcano seeps are also mostly CO2. Lake Nyos represents the only place where 100% of the gaseous output of a seep has been captured. I recall that the low CO2 attributed to volcanoes was based on a handful of samples.
So many things have been there for millennium but the first time somebody takes notice, it becomes a crisis.
Your tax dollars
at workbeing collected.For a so-called scientific paper, this paper seems to be fatally short of any science. Coming over all poetic about ‘ iridescent white pools containing high concentrations of carbon dioxide’ doesn’t really cut it as science; neither do comments about low pH and speculation about carbon capture and storage. What’s the hydration equilibrium constant for carbonic acid down there at about 25 bar and 288K? What chemistry is going on?
I’ve seen estimated of the CO2 output from a volcano that range all over the place. Does anyone know of a trusted source for the actual CO2 output of an average volcano? How many active underseas volcanoes there are? How many years equivalent of Fossil Fuels burning does an average Volcano represent? I’ve seen estimates that a single Volcano can produce the CO2 equivalent of the past 150 years of anthropogenic CO2. Can anyone confirm that statistic?
I believe there was a paper published in EOS a few years ago that was used to estimate total volcanic CO2. Trusted source? I’m not sure. I believe this is the article:
http://volcanoes.usgs.gov/hazards/gas/Gerlach-2011-EOS_AGU.pdf
There was an estimate of the total number of underwater volcanoes here:
http://www.iceagenow.com/Three_Million_Underwater_Volcanoes.htm
It’s just an estimate based on extrapolating a count over a limited area.
I’m a bit skeptical about the number of “150 years of anthropogenic CO2 from a single volcano:” I think the total volcanic CO2 is estimated as 0.12 Gigatonnes (as Carbon) per year. Extrapolating from the Lake Nyos seep and multiplying by 3 million subsea volcanoes gives 8.0 GT C/year, a substantial fraction of the putative 35 GT/year for anthropogenic carbon (Gerlach). The jury is very much out on this; the science is unsettled.
What is an “Average volcano”? You have volcanos that sit there for hundreds or thousands of years and do nothing, then suddenly blow their top (think Vesuvius, Mt St Helens). On the other hand there are those that are in a permanent state of eruption – Etna, Stromboli, etc.
Someone asked why the ‘pools’ of CO2 did not disperse. All you need is a small fissure leaking CO2 (or methane) to keep the supply up, to balance the amount dispersed by mixing and drifting away at the top. (CH4 + 2O2 = CO2 + 2H20).
A scientist who investigated the Lake Monoun disaster came up with the theory that the CO2 concentration at the bottom had got too great and caused the instability which resulted in the CO2 eruption. This was confirmed by a scientist investigating the Lake Nyos disaster, and eventually led to the possibility of a self-operating pump using gaseous CO2 created by it coming out of solution as the water was sucked up the pipe, initially by pumps to get it started. IIRC, it took about 3 days for the pipe to become a ‘self acting’ CO2 pump. This reference comes from a video I saw – possibly produced by the BBC.
I have not been able to find that video, but I found this which is a very good National Geographic documentary explaining the disasters. BTW, the fountain produced by the self acting CO2 pump was stated (elsewhere) to be 21 metres high.
CO2 Greece traps.
There’s something like a total of 80,000 km of spreading tectonic ridges on Earth, not only in each ocean but also places like Lake Baikal. The number of sub-aqueous vents has never been counted, so their emissions of methane, carbon dioxide, sulfur dioxide, hydrochloric acid, hydrofluoric acid, etc., has never been measured. Rather than succumbing to the temptation of premature exclamation, such careful observation and measurement might just be the scientific thing to do.
If these pools are high in CO2 and low pH then they’re perfect for getting an understanding of what happens to the sea in extremis. Are there any carbon-based lifeforms living in the pools? Is the temperature higher than in the surrounding water? Are corals being bleached? Are shells being eroded? Wouldn’t it be wonderful if some empirical science were to be done here!
It’s OK. The EU bank has just approved a loan to Greece so that it can pay debt/interest on debt, or rather pay loans the EU bank granted Greece. I mean, what could possibly go wrong with borrowing money to pay interest/debt on borrowed money?
80% of earth’s volcanoes are under the oceans. They spew CO2, amongst many other things, in amounts that dwarf the human contribution of CO2 to the atmosphere. To then suggest human activity CO2 drives the climate and is causing catastrophic global warming is simply childish ignorance.
Mostly I am trollish but here I think my comments will be relevant.
P Ward J Kirshvink The New History of Life refers to the idea that the highs and lows of O2 and CO2 have controlled all of Earth’s life history. Our speciation, the origin of live births, why dinos were upright — it is a great read.
Historically people have lived beside inland seas –Black, Med, etc., so it is no surprise that CO2 is noted there more than anywhere else. Homer’s Greeks were subject to CO2 releases, probably the Early Copper Age experienced CO2 floods as well. Of course history cant record what it cant see or identify. The closest history come to this is the Delphi Oracle.