This document summarizes a presentation about using natural CO2 vents as analogues to study potential environmental effects of CO2 leakage from carbon storage. It describes several examples of terrestrial and marine natural CO2 vents, including sites in Germany, Italy, and Japan. Parameters that can be investigated using these analogues include CO2 concentrations, chemical impacts on pH and metal mobilization, and biological impacts on microbes, vegetation, and animals. The presentation emphasizes that natural analogues provide realistic boundary conditions to validate experimental and modeling results and to test monitoring techniques.

1. Potential environmental effects of CO2 leakage in marine and terrestrial
environments: Understanding, monitoring, mitigation workshop
21st February 2012 – The University of Nottingham
Natural Analogues
How we can learn from nature
Giorgio Caramanna
giorgio.caramanna@nottingham.ac.uk

2. Outline
• Natural analogues
Where can we find them?
Why are they useful?
What can we investigate?
• A terrestrial example: the caldera of Laacher See (Germany)
• A marine example: shallow-water emissions in Italy and
deep-water emissions in Japan
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3. Natural analogues
• CO2 vents can be found in terrestrial and aquatic
environments and are generally associated with volcanic
and geothermal active areas.
• The source of the CO2 can be a degassing magmatic body,
the mantle or even the thermal decomposition of limestone
bedrock.
• The CO2 concentration of the emitted gas is variable and
there is often some % of other gases, typically SO2 and H2S.
• The fluxes range from a few litres to hundreds of litres per
minute.
• The vents follow the tectonic lineaments.
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4. Why natural analogues are useful
• The boundary conditions are far more realistic than any
possible laboratory simulation.
CO2 is generally emitted through large areas.
The emissions have lasted a long time.
There is a well-developed ecosystem.
• They can be used to validate results from laboratory
experiments and modelling.
• They can be used to test instruments and methods for
CO2 seepage detection and monitoring.
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5. Parameters to investigate
• CO2 concentrations as free or dissolved gas
Soil gas sampling
Airborne survey
Eddy covariance
Dissolved gas sensor
• Chemical impact
pH variations
Metals mobilization
• Biological impact
Microbes
Vegetation
Animals
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6. Laacher See

7. 7

8. Laacher See natural analogue
• The lake occupies one of about 100 quaternary eruptive
centres which spread over an area of 330 km2 in the East-
Eiffel volcanic province (Germany).
• The source of the CO2 is in the upper mantle from where
Mg-rich magma, formed by the melting of peridotite,
transports and releases the gas through the lower and
upper crust.
• The CO2 interacts with the groundwater originating high-
mineralized springs.
• The lake has a maximum depth of 52 m and CO2 vents are
located mostly along its north-eastern shore and along
some alignments underwater.
• The emitted CO2 is estimated at about 5,000 t/year.
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9. Gas eruption and shallow-water
ROV video courtesy of CO2GeoNet
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10. I. R. and Eddy Covariance
Pictures courtesy of BGS
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11. Kagoshima Bay
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12. 12

13. Kagoshima Bay natural analogue
• The Aira caldera and its post-caldera active volcano
Sakurajima are the dominant features of Kagoshima Bay.
• The caldera is supposed to be more than 22 *103 years old.
The last eruption of the Sakurajima was in 1914 and since
1955 there is a continuous ash emission from the crater.
• The maximum depth of the caldera is 200 m.
• On the seafloor, some vents emit high temperature fluids
(215oC) and gas composed of CO2, H2S, CH4 and N2.
• The vents have been studied by means of manned
submersibles and unmanned vehicles.
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14. AUV and ROV in deep-water
Courtesy of Kyushu University
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15. Panarea Island

16. Main vents location
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17. Panarea natural analogue
• Submerged caldera with emission of gas (mainly CO2) close
to the island of Panarea (Italy).
• In 2002, the area was affected by a gas burst with a strong
increase in the CO2 flow likely originated from a degassing
magmatic body.
• The flux of the vented CO2 ranges from a few litres to more
than 150 litres/minute with a total flux of up to 70,000 t/year.
•Due to the environmental conditions and the relatively
shallow water, it is possible to use the island as field-lab for
the development of monitoring techniques and to verify the
impact of high levels of CO2 on the marine ecosystem at costs
almost negligible as compared to high-seas research.
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18. Divers in shallow water
Courtesy of The University of Nottingham
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19. Free gas composition
Average free gas composition October 2011
89.37
%
90.00
80.00
70.00
60.00
50.00
40.00
30.00
20.00 3.91 5.68
1.55
10.00
0.00
O2 N2 CO2 H2S
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20. pH variations
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21. Lessons learned
• Reliability of detection and monitoring techniques.
CO2 is clearly identifiable as gas and from the
pH decrease.
Geochemical techniques are a reliable tool.
Biological stress (vegetations, microbes, macro
life-forms) can be used to identify the presence of
CO2 values above the baseline.
• The presence of gases other than CO2 should be
addressed for the realistic interpretation of the results.
• Good potentiality of natural analogues to be used as
testing facilities for innovative techniques and detection
instruments.
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22. Acknowledgements
• The University of Nottingham
• The Kyushu University and Dr. Kiminori Shitashima
• The University of Plymouth and Dr. Riccardo Rodolfo-
Metalpa for his diving collaboration in Panarea
•The INGV and Dr. Nunzia Voltattorni for the Panarea gas
analysis.
• The BGS
• The CO2GeoNet
• The BGR
•All of the colleagues who collaborated on the fieldwork
activity
•The NCCCS for hosting this workshop
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23. Thank you for your kind attention!
Questions?
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