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."
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.
The Woods Hole Oceanographic Institution is a private, non-profit organization on Cape Cod, Mass., dedicated to marine research, engineering, and higher education. Established in 1930 on a recommendation from the National Academy of Sciences, its primary mission is to understand the ocean and its interaction with the Earth as a whole, and to communicate a basic understanding of the ocean's role in the changing global environment. For more information, please visit http://www.
WHOI Media Office | EurekAlert!
Solving the mystery of carbon on ocean floor
06.12.2019 | University of Delaware
Great Barrier Reef study shows how reef copes with rapid sea-level rise
05.12.2019 | University of Sydney
University of Texas and MIT researchers create virtual UAVs that can predict vehicle health, enable autonomous decision-making
In the not too distant future, we can expect to see our skies filled with unmanned aerial vehicles (UAVs) delivering packages, maybe even people, from location...
With ultracold chemistry, researchers get a first look at exactly what happens during a chemical reaction
The coldest chemical reaction in the known universe took place in what appears to be a chaotic mess of lasers. The appearance deceives: Deep within that...
Abnormal scarring is a serious threat resulting in non-healing chronic wounds or fibrosis. Scars form when fibroblasts, a type of cell of connective tissue, reach wounded skin and deposit plugs of extracellular matrix. Until today, the question about the exact anatomical origin of these fibroblasts has not been answered. In order to find potential ways of influencing the scarring process, the team of Dr. Yuval Rinkevich, Group Leader for Regenerative Biology at the Institute of Lung Biology and Disease at Helmholtz Zentrum München, aimed to finally find an answer. As it was already known that all scars derive from a fibroblast lineage expressing the Engrailed-1 gene - a lineage not only present in skin, but also in fascia - the researchers intentionally tried to understand whether or not fascia might be the origin of fibroblasts.
Fibroblasts kit - ready to heal wounds
Research from a leading international expert on the health of the Great Lakes suggests that the growing intensity and scale of pollution from plastics poses serious risks to human health and will continue to have profound consequences on the ecosystem.
In an article published this month in the Journal of Waste Resources and Recycling, Gail Krantzberg, a professor in the Booth School of Engineering Practice...
03.12.2019 | Event News
15.11.2019 | Event News
15.11.2019 | Event News
06.12.2019 | Earth Sciences
06.12.2019 | Life Sciences
06.12.2019 | Information Technology