9:00 AM - 10:30 AM
[ACG34-P02] Implications of aerosol iron from smelting process on water-soluble iron deposition
Keywords:water-soluble iron, metal production, anthropogenic aerosol, mineral dust, air pollution
Atmospheric depositions of leachable iron (Fe) from anthropogenic (metal production and fossil fuel 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 apportionment, due to a lack of source-specific evaluation of Fe-laden aerosols (Ito et al., Sci. Adv., 2019). Here, the large uncertainties in the model estimates are investigated using different Fe emissions from metal production.
This study used the Integrated Massively Parallel Atmospheric Chemical Transport (IMPACT) model (Ito and Miyakawa, Environ. Sci. Technol., 2023). We updated the emission data set from anthropogenic sources, following the revised emission data set of the Community Emission Data System (CEDS). Here, smelting Fe emissions were estimated from the statistical database and emission factors of Fe for metal smelting (J. Geophys. Res. Atmos., 2020). The anthropogenic and lithogenic factors are evaluated by using high-time-resolution measurements of Fe-laden species in fine particulate matter at Fukue observational site in downstream region of East Asian outflow (Miyakawa et al., JpGU-AGU joint meeting 2020). The model prediction of aerosol Fe bioaccessibility is evaluated on a global scale (Ito et al., Sci. Adv., 2019; Npj Clim. Atmos. Sci., 2021).
The best agreement in anthropogenic factor of aerosol Fe concentrations with the field data is obtained with the low estimate of smelting Fe emission factors. The simulation with the higher estimates of smelting Fe emission factors indicates better agreement of aerosol Fe bioaccessibility with field data over oceans south of 45°S, whereas the simulation with the lower estimates of smelting Fe emission factors show better agreement with field data over the rest of the global ocean. Our simulation with the low estimate of smelting Fe emission confirms that anthropogenic aerosols play dominant roles in bioaccessible Fe deposition to the northwestern Pacific, compared to lithogenic sources. Our simulations with different estimates of smelting Fe emission factors suggest that Fe-containing particles co-emitted with sulfur dioxide from metal production substantially contribute to atmospheric bioaccessible Fe fluxes to the Southern Ocean. These findings highlight that accurate representation of aerosol Fe from metal production is a key to reduce large uncertainties in bioaccessible Fe deposition fluxes to the Southern Ocean.
This study used the Integrated Massively Parallel Atmospheric Chemical Transport (IMPACT) model (Ito and Miyakawa, Environ. Sci. Technol., 2023). We updated the emission data set from anthropogenic sources, following the revised emission data set of the Community Emission Data System (CEDS). Here, smelting Fe emissions were estimated from the statistical database and emission factors of Fe for metal smelting (J. Geophys. Res. Atmos., 2020). The anthropogenic and lithogenic factors are evaluated by using high-time-resolution measurements of Fe-laden species in fine particulate matter at Fukue observational site in downstream region of East Asian outflow (Miyakawa et al., JpGU-AGU joint meeting 2020). The model prediction of aerosol Fe bioaccessibility is evaluated on a global scale (Ito et al., Sci. Adv., 2019; Npj Clim. Atmos. Sci., 2021).
The best agreement in anthropogenic factor of aerosol Fe concentrations with the field data is obtained with the low estimate of smelting Fe emission factors. The simulation with the higher estimates of smelting Fe emission factors indicates better agreement of aerosol Fe bioaccessibility with field data over oceans south of 45°S, whereas the simulation with the lower estimates of smelting Fe emission factors show better agreement with field data over the rest of the global ocean. Our simulation with the low estimate of smelting Fe emission confirms that anthropogenic aerosols play dominant roles in bioaccessible Fe deposition to the northwestern Pacific, compared to lithogenic sources. Our simulations with different estimates of smelting Fe emission factors suggest that Fe-containing particles co-emitted with sulfur dioxide from metal production substantially contribute to atmospheric bioaccessible Fe fluxes to the Southern Ocean. These findings highlight that accurate representation of aerosol Fe from metal production is a key to reduce large uncertainties in bioaccessible Fe deposition fluxes to the Southern Ocean.