Modeling the Influence of Different Processes on Iron Solubilization in Mineral Aerosols: From the Gobi Desert to the North Pacific Ocean

Atmospheric transport is the only known means to deliver dissolved iron from the continents to remote oceanic areas. Dissolved iron is one of the necessary nutrients for photosynthesis of microscopic, single-celled marine organisms (phytoplankton) that grow abundantly in oceans around the world. Alteration of dissolved iron fluxes may substantially affect ocean ecosystem productivity and even exert a global-scale influence on climate by affecting the rate at which atmospheric CO2 is fixed by oceanic biota. On continents, iron mainly exists in forms of highly insoluble minerals (iron-oxides and iron-aluminosilicates) and the processes that can solubilize iron in mineral aerosols during their long-range transport remain poorly understood. In this work we attempt to elucidate the key processes that control the solubilization of iron in mineral aerosols using a simple Lagrangian box model to simulate the transport and chemical alteration of iron-containing mineral aerosols as they are transported from the east coast of China to the remote western North Pacific Ocean. Model parameters and initial conditions are set using a combination of soil and aerosol data from the Gobi Desert, as well as from measurements made during specific PEM-West B flights that encountered dust storm plumes over the Pacific Ocean that had originated in China. Our preliminary results indicate that the amount of acidic pollutants in the air along the dust transport pathways can have a significant effect on the amount of iron that is solubilized in advecting mineral aerosols. This suggests that there may be a link between the flux of the dissolved iron to the remote North Pacific Ocean and the rate at which pollutants such as sulfur dioxide, nitrogen oxides, and ammonia are emitted in East Asia.