Publication Date:
2014-03-28
Description:
Iron (Fe) limitation during the austral summer is a persistent characteristic of primary production in the Ross Sea, Antarctica. Recent observations reveal low dissolved Fe (dFe) concentrations in the Ross Sea polynya after the dFe winter reserve has been consumed in association with high rates of primary production, suggesting significant new sources of dFe are required to sustain the phytoplankton bloom during this period. The accumulation of locally-derived aeolian sand and dust (ASD) on sea ice is a potential source. To constrain aeolian Fe inputs from melting sea ice, we determined ASD mass accumulation rates as well as the total and soluble Fe content on first year sea ice in McMurdo Sound (Latitude 77.5ºS; Longitude 165ºE), southwestern (SW) Ross Sea. The mean ASD mass accumulation rate was ~1.5 g m -2 yr -1 , total Fe content of this ASD was 4 ± 1 wt % and the percentage of soluble Fe was 11 ± 1 %. Assuming our results are representative of the 7400 km 2 McMurdo Sound region, we use our mean estimate of the bulk aeolian dFe flux of 122.1 µmol m -2 yr -1 to calculate that aeolian Fe potentially supports between 9.0 x 10 9 and 4.1 x 10 11 mol C yr -1 (0.1-4.9 Tg C yr -1 ) of new primary production in McMurdo Sound. This equates to ~15 % of new primary production in the SW Ross Sea, suggesting that locally-derived aeolian dFe is a minor component of seasonal Fe supply. Consequently, this study highlights the need to quantify other sources of dFe to the Ross Sea region, which can potentially sustain phytoplankton blooms during the austral summer. In comparison to other estimates in the Antarctic region, McMurdo Sound has very high ASD and represents an upper limit of dFe that can be contributed to the ocean from melting sea ice in the Ross Sea.
Print ISSN:
0886-6236
Electronic ISSN:
1944-9224
Topics:
Biology
,
Chemistry and Pharmacology
,
Geography
,
Geosciences
,
Physics
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