A unique insight into the properties of iron aerosols in the Arctic Ocean

Science Highlights

31 January 2020

Gao and co-workers (2019, see reference below) collected size-segregated aerosols over 8 segments of the 2015 US GEOTRACES cruise (GN01) across the Arctic Ocean. They show that:

  • aerosol iron (Fe) had a single-mode size distribution, peaking at 4.4 μm in diameter, suggesting regional dust sources of Fe around the Arctic Ocean,
  • Fe in the coarse-mode particles accounted for ~68% of the aerosol Fe from all samples and 59% if sample M7 is excluded,
  • the low Fe/Ti ratio indicate that Fe was not enriched relative to average upper continental crust,
  • although the less abundant fraction, the fine dusts (<1µm) contain the most dissolvable fraction of iron but abundant organic ligands are also suspected to increase the Fe solubility and,
  • dry deposition rates of aerosol Fe decreased from 6.1 μmol m−2 yr−1 in the areas of ~56°N–80°N to 0.73 μmol m−2 yr−1 in the areas north of 80°N.

2020 GaoFigure: (a) Cruise tracks showing the coverage of eight sets (M1 – M8) of aerosol samples collected in the Arctic Ocean aboard the US Coast Guard Ice Breaker Healy during the period from 9th August 2015 to 12th October 2015. (b) Spatial variation of atmospheric concentrations of aerosol Fe in fine- and coarse-mode particles and total (coarse + fine) particles. Higher concentrations of aerosol Fe in samples M2 and M7 likely resulted from dust materials transported from nearby continental areas. (c) Atmospheric concentrations of total dissolvable Fe in fine aerosols were higher than those in coarse aerosols. One explanation is that smaller aerosols may provide larger surface areas relative to their volume for chemical reactions with other substances that promote Fe dissolution from dust. Click on the figure to view it larger.

Reference:

Gao, Y., Marsay, C. M., Yu, S., Fan, S., Mukherjee, P., Buck, C. S., & Landing, W. M. (2019). Particle-Size Variability of Aerosol Iron and Impact on Iron Solubility and Dry Deposition Fluxes to the Arctic Ocean. Scientific Reports, 9(1), 16653. https://doi.org/10.1038/s41598-019-52468-z

Latest highlights

Rare Earth and neodymium isotope cycles in the abyssal Pacific Ocean are shaking up the paradigm established for particle reactive tracers

Du and colleagues demonstrate the importance of the abyssal sediment source in the control of the trace element and isotopes marine distribution.

Anthropogenic iron impact on the surface productivity in the Pacific Transition Zone

Hawco and colleagues investigated the influence of industrial emissions on oceanic iron supply and its ecological consequences in the North Pacific.

Trace metal effluxes from Peruvian shelf sediments

Liu and co-authors compared four methods to estimate dissolved iron fluxes from Peruvian shelf sediments, revealing large variability.

Coupling copper and neodymium data highlights the importance of the margin sources for the copper oceanic cycle

Lemaitre and co-workers analysed the dissolved concentrations and isotopes along the GEOVIDE (GA01) section in the North Atlantic Ocean.

Rechercher