Dissolution of dust borne primary iron(II) silicates sourced from physically weathered regions, and its impact on iron and silica utilization and CO2 drawdown by …

Dust-borne nutrients, especially iron (Fe), are important to phytoplankton growth in the ocean. In the Fe-limited Southern Ocean, dust-borne Fe fertilization of silica-frustule-forming diatoms is thought to be responsible for about half of the CO 2 drawdown in the last glacial cycle. Previous work has shown that physical weathering by glaciers mobilizes dust-borne Fe contained in Fe (II) silicates, which is more bioavailable to diatoms than the Fe in non-glaciogenic and chemically weathered Fe (III) oxides. Additionally, previous research suggests that Fe-limited phytoplankton benefit from surface contact with Fe-rich particles, which may be due to diffusion limitation or active dissolution. Here we investigate the potential for primary Fe (II) silicates to provide both Fe and silica (Si) to diatoms in the Southern Ocean, where Fe and Si can co-limit diatom growth. We investigate the extent to which primary Fe (II) silicates are …