Significant impact of lithogenic dissolution from subantarctic volcanic islands on the regional marine silicon cycle

A significant contribution of lithogenic silicon (Si) from subantarctic volcanic islands, specifically Heard and McDonald Islands, has been identified as a major source of dissolved Si in the regional marine environment. This study reveals that the dissolution flux of lithogenic Si around these islands is among the highest globally, with an estimated specific flux of 3.7 ± 2.3 × 10^6 mol km^-2 yr^-1. The findings suggest that active volcanic activity and subglacial erosion on Heard Island are likely responsible for this high dissolution rate. The research utilized Si isotopic signatures to differentiate between dissolved and biogenic Si, demonstrating that lithogenic Si dissolution significantly impacts the regional marine silicon cycle and has traceable biogeochemical effects over the Northern Kerguelen Plateau.

Cotard, E., Deteix, V., Vivier, F., Dapoigny, A., Caquineau, S., & Cardinal, D. (2025). Significant impact of lithogenic dissolution from subantarctic volcanic islands on the regional marine silicon cycle. Limnology and Oceanography, 70(12), 3711–3724. Portico. https://doi.org/10.1002/lno.70243