Methods for removing CO₂ from the atmosphere are urgently needed to keep the global temperature increase below 1.5°C. A promising CO₂ removal technology is enhanced silicate weathering (ESW) in coastal systems. The technology is based on natural silicate mineral weathering, which releases alkalinity and thereby increases the seawater’s capacity to dissolve CO₂. It is though that silicate weathering can be sped up by introducing the minerals in coastal sediments where waves, currents and bioturbation can stimulate the weathering. Although model and laboratory studies suggest ESW is feasible, research on the process in natural conditions is lacking. Hence, the CO₂ sequestration efficiency and risks when applying ESW in the field are largely unknown. We present results from the first and longest-running mesocosm experiment investigating ESW and associated CO₂ uptake in coastal marine sediments. In tanks containing natural sediment, we have studied biogeochemical cycling after treatment with the fast-weathering silicate mineral olivine. Lugworms were added to some tanks to investigate the effect of bioturbation on the olivine dissolution rate and the impact of olivine addition on biota. 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 discuss the large-scale effect of ESW on biogeochemical cycling in coastal ecosystems.

Primary Presenter: Astrid Hylén, University of Antwerp (astrid.hylen@uantwerpen.be)

Authors:

Astrid Hylén, Department of Biology, University of Antwerp, Belgium  ()

Matthias Kreuzburg, Department of Biology, University of Antwerp, Belgium  ()

Saïd De Wolf, Department of Biology, University of Antwerp, Belgium  ()

Laurine Burdorf, Agentschap Innoveren & Ondernemen, Belgium  ()

Géraldine Fiers, Department of Geology, Ghent University, Belgium  ()

Cedric Goossens, Department of Biology, University of Antwerp, Belgium  ()

Benjamin Van Heurck, Department of Biology, University of Antwerp, Belgium  ()

Hannelore Theetaert, Flanders Marine Institute, Belgium  ()

Silke Verbrugge, Flanders Marine Institute, Belgium  ()

Veerle Cnudde, Department of Geology, Ghent University, Belgium  ()

André Cattrijsse, Flanders Marine Institute, Belgium  ()

Filip Meysman, Department of Biology, University of Antwerp, Belgium  ()