Abstract
Lithogenic and pyrogenic aerosols supply potentially bioavailable iron to the open ocean where increases in the supply could result in a decrease in atmospheric carbon dioxide concentrations. This paper reviews recent progresses in observations, laboratory simulations, aerosol modelling and ocean biogeochemical modelling, focusing on pyrogenic iron. New data on emission, chemistry and dissolution kinetics confirmed a considerably higher iron solubility of pyrogenic aerosol than natural dust. State-of-the-art aerosol models highlighted that pyrogenic sources contribute to the total atmospheric supply of dissolved iron about 20% into the global ocean (Ito et al., Science Advances, 2019). The fertilizing effect of this “new” iron source has been increasingly examined in ocean models, some of which reported higher efficiency of pyrogenic iron to enhance marine productivity than lithogenic sources. It is, however, still a major challenge in future research to quantitatively understand and predict the high variability, complex aerosol and seawater chemistry of this iron source and diverse marine responses.
