Detection and quantification of a release of carbon dioxide gas at the seafloor using pH eddy covariance and measurements of plume advection

Koopmans, Dirk; Meyer, Volker; Schaap, Allison ORCID: https://orcid.org/0000-0001-5391-0516; Dewar, Marius; Färber, Paul; Long, Matthew; Gros, Jonas; Connelly, Douglas; Holtappels, Moritz. 2021 Detection and quantification of a release of carbon dioxide gas at the seafloor using pH eddy covariance and measurements of plume advection. International Journal of Greenhouse Gas Control, 112, 103476. https://doi.org/10.1016/j.ijggc.2021.103476

Before downloading, please read NORA policies.

Preview

Text
Koopmans 2021 IJGGC Eddy covariance for STEMM.pdf - Published Version
Available under License Creative Commons Attribution 4.0.
Download (5MB) | Preview

Official URL: http://dx.doi.org/10.1016/j.ijggc.2021.103476

Abstract/Summary

We detected a controlled release of CO2 (g) with pH eddy covariance. We quantified CO2 emission using measurements of water velocity and pH in the plume of aqueous CO2 generated by the bubble streams, and using model predictions of vertical CO2 dissolution and its dispersion downstream. CO2 (g) was injected 3 m below the floor of the North Sea at rates of 5.7–143 kg d − 1. Instruments were 2.6 m from the center of the bubble streams. In the absence of injected CO2, pH eddy covariance quantified the proton flux due to naturally-occurring benthic organic matter mineralization (equivalent to a dissolved inorganic carbon flux of 7.6 ± 3.3 mmol m − 2 d − 1, s.e., n = 33). At the lowest injection rate, the proton flux due to CO2 dissolution was 20-fold greater than this. To accurately quantify emission, the kinetics of the carbonate system had to be accounted for. At the peak injection rate, 73 ± 13% (s.d.) of the injected CO2 was emitted, but when kinetics were neglected, the calculated CO2 emission was one-fifth of this. Our results demonstrate that geochemical techniques can detect and quantify very small seafloor sources of CO2 and attribute them to natural or abiotic origins.

Item Type:	Publication - Article
Digital Object Identifier (DOI):	https://doi.org/10.1016/j.ijggc.2021.103476
ISSN:	1750-5836
Date made live:	23 Nov 2021 16:01 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/531358

Item Type:

Publication - Article

Digital Object Identifier (DOI):

https://doi.org/10.1016/j.ijggc.2021.103476

ISSN:

1750-5836

Date made live:

23 Nov 2021 16:01 +0 (UTC)

URI:

https://nora.nerc.ac.uk/id/eprint/531358