About 40% of global ocean primary productivity by area is limited by supply of soluble iron. Anthropogenic combustion sources of iron represent 5-8% of the total iron emissions but represent around 50-90% of the total soluble iron emissions and their quantification is important in estimating the impacts of soluble iron deposition on nitrogen-fixing phytoplankton and carbon uptake from the atmosphere. This study estimates total iron emissions from anthropogenic combustion sources and provides the first estimate of combustion-iron emissions as a combination of different minerals instead of a single component. This inventory provides a physically-based representation of iron emissions and solubility for better simulation of transport and deposition, radiative forcing, and the ocean biogeochemistry.

Iron is emitted as oxide (hematite, magnetite, and goethite), clayey (kaolinite and illite), and sulfate (ferric and ferrous sulfate) minerals. These minerals have different solubility, reactivity toward atmospheric acidic and organic species, and radiative forcing signs and intensities. by the iron-containing minerals emitted from anthropogenic combustion sources. Measured iron mineralogy of particulate matter from different fossil fuel combustion are multiplied by total iron emissions to estimate mineral-iron emissions. Fuel-specific iron solubility is estimated as a weighted average of particulate matter mineralogy and mineral iron solubility. Soluble iron emissions are estimated by multiplying the fuel-specific solubility by the iron emissions.

Global total combustion-iron emissions for the year 2010 are estimated to be 0.4 (0.03-1.4) TgFe/yr and 0.42 (0.04-2.3) TgFe/yr in PM₁ and PM_1-10 size bins. Mineral emissions from anthropogenic combustion sources are estimated to be 0.09 (0.008-0.4) Tg/yr hematite, 0.33 (0.03-1.5) Tg/yr Magnetite, 0.015 (0.003-0.05) Tg/yr Ferric sulfate, and 0.31 (0.03-1.5) Tg/yr Kaolinite+Illite in total PM. Mineralogy-based soluble iron emissions are 16 (3-50) Gg Soluble Fe/yr and 11 (1-55) Gg Soluble Fe/yr in PM₁ and PM_1-10 size bins.