The effect of submarine CO2vents on seawater: Implications for detection of subsea carbon sequestration leakage

• Published in: Limnology and Oceanography
• Main Authors: Botnen, Helle Augdal, Omar, Abdirahman M., Thorseth, Ingunn, Johannessen, Truls, Alendal, Guttorm
• Format: Article in Journal/Newspaper
• Language: English
• Published: ASLO (Association for the Sciences of Limnology and Oceanography) 2015
• Subjects: Greenland; Jan Mayen; Greenland Sea; Jan Mayen Island
• Online Access: https://oceanrep.geomar.de/id/eprint/29179/; https://oceanrep.geomar.de/id/eprint/29179/1/Botnen.pdf; https://doi.org/10.1002/lno.10037

The effect of submarine carbon dioxide (CO2) vents on seawater carbonate chemistry have been determined using hydrographical and marine carbonate data obtained from two submarine hydrothermal vent fields, as well as a reference station, all near the Jan Mayen Island in the Norwegian-Greenland Sea. We have shown that one can successfully determine the excess carbon that enters the seawater from the vents by applying a modified version of a back-calculation technique, which is traditionally used to study the invasion of excess atmospheric CO2 in the surface ocean. As a result of this excess carbon, total dissolved inorganic carbon (CT) in the seawater surrounding the vents was on average 12 μmol kg−1 (1-30 μmol kg−1) higher compared to samples obtained from a reference station outside the venting areas. The observed excess CT was most significant between 100 m and 200 m but was noticeable in all depths with the exception of the upper 10-20 m. The absence of a venting CO2 signal in the surface water and the realism of the results are discussed. We believe the present method is promising for monitoring (detection and quantification) of CO2 leakage into the water column due to its high sensitivity and readiness for automation.