Glass

Global dissolution flux of lithogenic silicon from beaches

Coordination

Jill Sutton, France Floc’h, Nicolas Le Dentec

Project type

International

Funding

ISBlue; ANR-17- EURE-0015

Project duration

Start Date

27/04/2024

End Date

Links

Silicon (Si) is the second most abundant element in the Earth’s crust. The weathering of the Earth’s crust is a key process in the control of atmospheric CO2 and results in the generation of silicic acid (dSi; Si(OH)4) in aqueous environments. For several decades, the study of the marine Si cycle has been of significant scientific interest for oceanographers, in particular its role in regulation of the global carbon cycle. A new source of Si was recently discovered (Fabre et al. 2019) resulting from the dissolution of sand grains in the nearshore zone due to shear stresses exerted by wave action on sediments in the surf and swash zone. This recently discovered source proposed by Fabre et al. (2019) might significantly increase the current estimate for the total input flux (14.8 Tmol Si yr^-1, Tréguer et al. 2021) of the modern marine Si cycle. Considering that one-third of the world’s shoreline is sandy beaches (Ludjendijk et al., 2018), Fabre et al. (2019) have evaluated a potential increase of total input flux of 25-32%. This result is extrapolated from laboratory experiments at 25°C where a mixture of "Fontainebleau sand" (pure quartz) and abiotic commercial filtered seawater is simply shaken, which does not re-create realistic conditions of a marine environment. Therefore, the question that can be asked is: Under realistic conditions, is the dissolution of sand grains in the swash zone of beaches an important contribution to the marine silicon cycle?