Giorgio Caramanna

giorgio.caramanna@nottingham.ac.uk

Natural Analogues How we can learn from nature

Potential environmental effects of CO2 leakage in marine and terrestrial

environments: Understanding, monitoring, mitigation workshop 21st February 2012 – The University of Nottingham

• 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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Outline

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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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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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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

Laacher See

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• 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.

Laacher See natural analogue

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Gas eruption and shallow-water

ROV video courtesy of CO2GeoNet

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Pictures courtesy of BGS

I. R. and Eddy Covariance

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Kagoshima Bay

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• 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.

Kagoshima Bay natural analogue

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AUV and ROV in deep-water

Courtesy of Kyushu University

Panarea Island

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Main vents location

• 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.

Panarea natural analogue

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Divers in shallow water

Courtesy of The University of Nottingham

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Free gas composition

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Average free gas composition October 2011

O2 CO2 N2 H2S

3.91 5.68 1.55

89.37

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pH variations

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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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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

Thank you for your kind attention!

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Questions?