Highly bioavailable dust-borne iron delivered to the Southern Ocean during glacial periods

Significance Dust-borne iron fertilization of Southern Ocean phytoplankton contributes to lower glacial atmospheric CO 2 . Previous studies evaluating the impact of dust on climate estimate bioavailable iron using total iron fluxes in sediment cores. Thus, all iron is considered equally bioavailable over geologic time, despite evidence that glaciers mobilize highly bioavailable iron from bedrock, which winds can deliver to the Southern Ocean....