EGU21-6330
https://doi.org/10.5194/egusphere-egu21-6330
EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Effect of different rates and modes of artificial upwelling on particle flux and potential POC deep export

Moritz Baumann1, Jan Taucher1, Allanah Joy Paul1, Malte Heinemann2, Mari Vanharanta3, Lennart Thomas Bach4, Kristian Spilling3, Joaquin Ortiz-Cortes1, Javier Arístegui5, and Ulf Riebesell1
Moritz Baumann et al.
  • 1GEOMAR Helmholtz-Centre for Ocean Research Kiel, Kiel, Germany
  • 2Institute for Geosciences, Christian-Albrechts-Universität zu Kiel, Kiel, Germany
  • 3Marine Research Centre, Finnish Environment Institute, Helsinki, Finland
  • 4Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, Tasmania, Australia
  • 5Instituto de Oceanografía y Cambio Global, IOCAG, Universidad de Las Palmas de Gran Canaria ULPGC, Las Palmas, Spain

To counteract climate change, measures to actively remove carbon dioxide from the atmosphere are required, since the reduction of global CO2 emissions alone will not suffice to meet the 1.5 °C goal of the Paris agreement. Artificial upwelling in the ocean has been discussed as one such carbon dioxide removal technique, by fueling primary production in the surface ocean with nutrient-rich deep water and thereby potentially enhancing downward fluxes of organic matter and carbon sequestration. In this study we tested the effect of different rates and modes of artificial upwelling on carbon export and its potential attenuation with depth in a five-week mesocosm experiment in the subtropical Northeast Atlantic. We fertilized oligotrophic surface waters with different amounts of deep water in a pulsed (deep water fertilization once at the beginning) and a continuous manner (deep water fertilization every four days) and measured the resulting export flux as well as sinking velocities and respiration rates of sinking particles. Based on this, we applied a simple one-dimensional model to calculate flux attenuation. We found that the export flux more than doubled when fertilizing with deep water, while the C:N ratios of produced organic matter increased from values around Redfield (6.6) to ~8-13. The pulsed form of upwelling resulted in a single export event, while the continuous mode led to a persistently elevated export flux. Particle sinking velocity and remineralization rates were highly variable over time and showed differences between upwelling modes. We stress the importance of experiments with a prolonged application of artificial upwelling and studies including real world open water application to validate the CO2 sequestration potential of artificial upwelling.

How to cite: Baumann, M., Taucher, J., Paul, A. J., Heinemann, M., Vanharanta, M., Bach, L. T., Spilling, K., Ortiz-Cortes, J., Arístegui, J., and Riebesell, U.: Effect of different rates and modes of artificial upwelling on particle flux and potential POC deep export, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-6330, https://doi.org/10.5194/egusphere-egu21-6330, 2021.

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