The origin of lithogenic sediment in the south-western Ross

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TitleThe origin of lithogenic sediment in the south-western Ross Sea and implications for iron fertilizationAbstractSummer iron (Fe) fertilization in the Ross Sea has previously been observed in association with diatom productivity, lithogenic particles and excess Fe in the water column. This productivity event occurred during an early breakout of sea ice via katabatic winds, suggesting that aeolian dust could be an important source of lithogenic Fe required for diatom growth in the Ross Sea. Here we investigate the provenance of size-selected dust deposited on sea ice in McMurdo Sound, south-western (SW) Ross Sea. The isotopic signature of McMurdo Sound dust (0.70533 less than 87Sr/86Sr less than 0.70915 and -1.1<ÏµNd(0) less than 3.45) confirms that dust is locally sourced from the McMurdo Sound debris bands and comprises a two-component mixture of McMurdo Volcanic Group and southern Victoria Land lithologies. In addition, the provenance of lithogenic sediment trapped in the water column was investigated, and the isotopic signature (ÏµNd(0)=3.9, 87Sr/86Sr=0.70434) is differentiated from long-range transported dust originating from South America and Australia. Elevated lithogenic accumulation rates in deeper sediment traps in the Ross Sea suggest that sinking particles in the water column cannot simply result from dust input at the surface. This discrepancy can be best explained by significant upwelling and remobilization of lithogenic Fe from the sea floor. Copyright 2016 Antarctic Science Ltd.AcknowledgementsWe would like to thank Antarctica New Zealand and Scott Base personnel for logistics support. Thank you to Jane Chewings, Associate Professor Brent Alloway and Assistant Professor Ana Aguilar-Islas for the collection of McMurdo Sound and Granite Harbour dust samples. Additional thanks to Professor Robert Dunbar for Chinstrap sediment trap samples from the ROAVERRS mooring programme. V.H.L.W would like to thank Curtin University (Australian Postgraduate Award and Curtin Research Scholarship) and Antarctic Science (Antarctic Science Bursary) for scholarship and other funding support. This project was funded by Curtin University (Curtin Research Fellowship to R.E.: RES-SE-DAP-AW-47679-1), and New Zealand Ministry of Science and Innovation through contracts to Victoria University of Wellington (Contracts: VUW0704; RDF-VUW1103) and GNS Science (Contracts: 540GCT32; C05X1001). Isotopic analyses for 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. Thank you to Karin Wallner and Hans SchÃ¶berg for technical support. The isotopic dataset for this paper is freely available from the Curtin University Research Data repository http://doi.org/10.4225/06/5643EBA1C8473. The chlorophyll a data was obtained freely from the Sea-Viewing Wide Field-of-View Sensor (http://giovanni.gsfc.nasa.gov/). Additional thanks for the helpful comments and suggestions of Jeroen de Jong and an anonymous reviewer that aided in revision of this manuscript.

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1st AuthorWinton, V.AuthorWinton, V.Dunbar, G.Atkins, C.Bertler, N.Delmonte, B.Andersson, P.Bowie, A.Edwards, R.Year2016JournalAntarctic ScienceVolume28Number4Pages250-260DOI10.1017/S095410201600002XURLhttps://www.scopus.com/inward/recor.....95be09aee59ed1e35799cb342KeywordsBacillariophyta, rank5Author KeywordsAntarcticadustdust provenanceironMcMurdo Sound

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TypeArticleCitationWinton, V., Dunbar, G., Atkins, C., Bertler, N., Delmonte, B., Andersson, P., Bowie, A. and Edwards, R. (2016). The origin of lithogenic sediment in the south-western Ross Sea and implications for iron fertilization. Antarctic Science, 28(4): 250-260 IdentifierWinton2016bRelevancerank5

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Bertler, N.