Atmospheric Iron Dynamics and Oceanic Biogeochemistry

Atmospheric iron plays a pivotal role in oceanic biogeochemistry by regulating primary productivity, carbon sequestration and nutrient cycling. Mineral dust, combustion aerosols and biomass burning release particulate iron into the atmosphere, where physicochemical processing—driven by acidity, organic ligands and photochemistry—modulates the fraction of iron that dissolves into bioavailable forms. Deposition of soluble iron to surface waters alleviates iron limitation in high-nitrate, low-chlorophyll regions, stimulating phytoplankton growth and enhancing the biological carbon pump. Anthropogenic activities have altered both the magnitude and speciation of airborne iron, with implications for regional ecosystems, climate feedbacks and air quality. Advances in isotopic tracing, laboratory kinetics and global modelling have improved quantification of sources, atmospheric transformation pathways and deposition fluxes. Emerging field studies and model projections highlight the sensitivity of iron solubility to aerosol acidity, oxalate concentrations and changing dust emissions under future climate and socioeconomic scenarios. A comprehensive understanding of atmospheric iron dynamics is therefore essential for predicting marine ecosystem responses, refining Earth-system models and informing climate-mitigation strategies.

Research from Nature Portfolio

Recent studies have revealed that trace metals released from natural and anthropogenic aerosols dissolve at variable rates, influencing phytoplankton community composition and biogeochemical loops over days to weeks. Investigations into combustion-derived iron demonstrate that inclusion of magnetite substantially increases estimates of soluble anthropogenic iron deposition to the Southern Ocean, altering both nutrient supply and radiative forcing. Isotopic analysis of aerosol δ56Fe has enabled discrimination between crustal dust and combustion sources, revealing that existing models underestimate the flux of anthropogenic soluble iron to remote ocean basins.

Atmospheric Iron Dynamics and Oceanic Biogeochemistry publication trend

The graph below shows the total number of articles in atmospheric iron dynamics and oceanic biogeochemistry across all publications each year (not limited to Nature Index journals).

Technical terms

Bioavailable iron: Fraction of atmospheric iron that dissolves into forms readily assimilated by marine phytoplankton.

Soluble iron deposition: Flux of dissolved iron compounds from the atmosphere to the ocean surface.

Aerosol acidity: Degree of acidity within aerosol water, determined by pH and inorganic anions, that promotes iron dissolution.

High-nitrate, low-chlorophyll (HNLC): Ocean regions with abundant macronutrients but low phytoplankton growth due to iron limitation.

References

1. Aerosol Iron from Metal Production as a Secondary Source of Bioaccessible Iron. Environmental Science and Technology (2023).
2. Pre‐Industrial, Present and Future Atmospheric Soluble Iron Deposition and the Role of Aerosol Acidity and Oxalate Under CMIP6 Emissions. Earth's Future (2023).
3. Air pollution–aerosol interactions produce more bioavailable iron for ocean ecosystems. Science Advances (2017).
4. Aerosol Deposition Impacts on Land and Ocean Carbon Cycles. Current Climate Change Reports (2017).
5. Delivery of anthropogenic bioavailable iron from mineral dust and combustion aerosols to the ocean. Atmospheric Chemistry and Physics (2016).
6. Anthropogenic combustion iron as a complex climate forcer. Nature Communications (2018).
7. Iron dissolution kinetics of mineral dust at low pH during simulated atmospheric processing. Atmospheric Chemistry and Physics (2011).
8. Sources, transport and deposition of iron in the global atmosphere. Atmospheric Chemistry and Physics (2015).
9. Effect of atmospheric organic complexation on iron-bearing dust solubility. Atmospheric Chemistry and Physics (2013).
10. Aerosol trace metal leaching and impacts on marine microorganisms. Nature Communications (2018).
11. Tracing and constraining anthropogenic aerosol iron fluxes to the North Atlantic Ocean using iron isotopes. Nature Communications (2019).