Constraints on contribution of anthropogenic and lithogenic iron in aerosols using high-time-resolution measurements of trace elements

Atmospheric depositions of leachable iron (Fe) from anthropogenic (metal production, fossil fuel and biofuel combustion), lithogenic (mineral dust), and pyrogenic (open biomass burning) aerosols represent important external sources of micronutrients to the open ocean, which could affect climate through marine biogeochemical feedbacks. However, significant uncertainties remain in the source fluxes, partly due to a lack of source-specific evaluation of Fe-laden aerosols. In this presentation, we evaluate the aerosol chemical transport model (IMPACT), using ground-based datasets of trace elements. The IMPACT model generally reproduced the observed data of Fe concentrations in fine particles at Fukue island during spring after the adjustment of emission source strengths to the measurements. The continuous monitoring data and these constrains on aerosol transport model offer improvements in the source apportionment of aerosol Fe. Our result reveals that particulate air pollution due to human activities is the major contributor of atmospheric bioaccessible iron (Fe) input to most portions of contemporary oceans, although it is the minor contributor of total Fe, compared to mineral dust and wildfires. This finding may help to draw more attention on mine air pollution, which is most likely responsible for the adverse health on the communities next to the mine industry, and its ecological effect on marine biome.