[Nemo_bis]

Fascinating read:

> A key question concerns the amount of iron dust that would be required to induce draw down of CO2 from the atmosphere. [...] In total, this estimate concludes that ~2.8 million tons of biogenic iron oxides would be delivered over 100 days per year to the iron-limited regions of the global ocean to reach conditions where iron was not limiting primary productivity.

Many other sources are available at https://en.wikipedia.org/wiki/Iron_fertilization#References and friends, please add this one too!