Multiple sources of soluble atmospheric iron to Antarctic waters

V. H.L. Winton, R. Edwards, B. Delmonte, A. Ellis, P. S. Andersson, A. Bowie, N. A.N. Bertler, P. Neff, A. Tuohy

Research output: Contribution to journalArticlepeer-review

28 Scopus citations

Abstract

The Ross Sea, Antarctica, is a highly productive region of the Southern Ocean. Significant new sources of iron (Fe) are required to sustain phytoplankton blooms in the austral summer. Atmospheric deposition is one potential source. The fractional solubility of Fe is an important variable determining Fe availability for biological uptake. To constrain aerosol Fe inputs to the Ross Sea region, fractional solubility of Fe was analyzed in a snow pit from Roosevelt Island, eastern Ross Sea. In addition, aluminum, dust, and refractory black carbon (rBC) concentrations were analyzed, to determine the contribution of mineral dust and combustion sources to the supply of aerosol Fe. We estimate exceptionally high dissolved Fe (dFe) flux of 1.2 × 10-6 g m-2 y-1 and total dissolvable Fe flux of 140 × 10-6 g m-2 y-1 for 2011/2012. Deposition of dust, Fe, Al, and rBC occurs primarily during spring-summer. The observed background fractional Fe solubility of ~0.7% is consistent with a mineral dust source. Radiogenic isotopic ratios and particle size distribution of dust indicates that the site is influenced by local and remote sources. In 2011/2012 summer, relatively high dFe concentrations paralleled both mineral dust and rBC deposition. Around half of the annual aerosol Fe deposition occurred in the austral summer phytoplankton growth season; however, the fractional Fe solubility was low. Our results suggest that the seasonality of dFe deposition can vary and should be considered on longer glacial-interglacial timescales.

Original languageEnglish (US)
Pages (from-to)421-437
Number of pages17
JournalGlobal Biogeochemical Cycles
Volume30
Issue number3
DOIs
StatePublished - Mar 1 2016
Externally publishedYes

Bibliographical note

Funding Information:
This work is a contribution to the Roosevelt Island Climate Evolution (RICE) Programme, funded by national contributions from New Zealand, Australia, Denmark, Germany, Italy, the People's Republic of China, Sweden, UK, and the USA. Logistic support was provided by Antarctica New Zealand (K049) and the US Antarctic Program.We would like to thank Antarctica New Zealand and Scott Base personnel for logistics support. Thank you to the RICE 2012/2013 team for assisting in the collection of samples from Roosevelt Island. V.H.L.W. would like to thank Curtin University for scholarship support (Australian Postgraduate Award and Curtin Research Scholarship). This project was funded by Curtin University, Victoria University of Wellington (RDF-VUW1103), GNS Science (540GCT32), the University of Milano-Bicocca, and the Swedish Museum of Natural History. Access to HR-ICP-MS instrumentation at Curtin University was facilitated through ARC LIEF funding (LE130100029). Thank you to K. Jarrett for technical assistance. Isotopic analyses for dust provenance characterization were carried out at the Swedish Museum of Natural History and were supported by the Department of Geosciences, Swedish Museum of Natural History. The authors acknowledge the use of equipment, scientific, and technical assistance of the Curtin University Electron Microscope Facility, which has been partially funded by the University, State, and Commonwealth Governments. We would like to acknowledge the Norwegian Polar Institute for the use of the Qantarctica package. The data set for the RICE 2012/2013 1.5m snow pit is available through the Curtin University Research Data repository http://doi.org/10.4225/ 06/565BCE14467D0 and supporting data are also included as tables in SI files. Additional thanks for the helpful comments and suggestions of Bess Koffman and an anonymous reviewer that aided in revision of this manuscript

Keywords

  • Antarctica
  • Roosevelt Island
  • Ross Sea
  • black carbon
  • dust
  • iron

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