EGU23-14128, updated on 17 Jun 2024
https://doi.org/10.5194/egusphere-egu23-14128
EGU General Assembly 2023
© Author(s) 2024. This work is distributed under
the Creative Commons Attribution 4.0 License.

Ocean alkalinity enhancement through enhanced silicate weathering in coastal areas: a long-term mesocosm study

Astrid Hylén1, Matthias Kreuzburg1, Saïd De Wolf1, Laurine Burdorf1,2, Géraldine Fiers3, Cedric Goossens1, Benjamin Van Heurck1, Hannelore Theetaert4, Silke Verbrugge4, Veerle Cnudde3, André Cattrijsse4, and Filip Meysman1
Astrid Hylén et al.
  • 1Department of Biology, University of Antwerp, Belgium
  • 2Agentschap Innoveren & Ondernemen, Belgium
  • 3Department of Geology, Ghent University, Belgium
  • 4Flanders Marine Institute, Belgium

Enhanced silicate weathering (ESW) in coastal environments is a promising method for ocean alkalinity enhancement. The idea behind ESW is to generate alkalinity by application of silicate minerals in coastal areas, where waves, currents and bioturbation can speed up the weathering rate. Due to its potentially large CO2 sequestration capacity and relatively high technological readiness, allowing rapid upscaling, coastal ESW currently receives substantial interest from researchers and policymakers. However, the vast majority of studies on ESW have been conducted in idealised laboratory conditions, while research on the method in natural environments is lacking. As a result, the CO2 sequestration efficiency and environmental risks when applying ESW in the field remain largely unknown.

Here we present results from the first and longest-running mesocosm experiment investigating ESW and associated CO2 uptake in coastal marine sediments. Using tanks containing one square meter of natural seafloor each, we have studied biogeochemical cycling in sediment treated with the fast-weathering silicate mineral olivine. Lugworms (Arenicola marina) were added to some tanks to investigate the effect of bioturbation on the olivine dissolution rate, as well as the impact of olivine addition on biota. In the mesocosms, we quantified the sedimentary release of alkalinity and other weathering end-products (trace metals and dissolved silicate). Five years into the experiment, olivine dissolution is obvious from an elevated sedimentary alkalinity release and decreased average olivine grain size. The elevated alkalinity release has further led to higher CO2 sequestrations in tanks with olivine. Based on the results from this unique mesocosm setup, we will discuss the large-scale effect of ESW on biogeochemical cycling in coastal ecosystems.

How to cite: Hylén, A., Kreuzburg, M., De Wolf, S., Burdorf, L., Fiers, G., Goossens, C., Van Heurck, B., Theetaert, H., Verbrugge, S., Cnudde, V., Cattrijsse, A., and Meysman, F.: Ocean alkalinity enhancement through enhanced silicate weathering in coastal areas: a long-term mesocosm study, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14128, https://doi.org/10.5194/egusphere-egu23-14128, 2023.