The distribution and stabilisation of dissolved Fe in deep-sea hydrothermal plumes

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118

作者：

SA Bennett，EP Achterberg，DP Connelly，PJ Statham，GR Fones，CR German

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摘要：

We have conducted a study of hydrothermal plumes overlying the Mid-Atlantic Ridge near 5° S to investigate whether there is a significant export flux of dissolved Fe from hydrothermal venting to the oceans. Our study combined measurements of plume-height Fe concentrations from a series of 6 CTD stations together with studies of dissolved Fe speciation in a subset of those samples. At 2.5km down plume from the nearest known vent site dissolved Fe concentrations were 20nM. This is much higher than would be predicted from a combination of plume dilution and dissolved Fe(II) oxidation rates, but consistent with stabilisation due to the presence of organic Fe complexes and Fe colloids. Using Competitive Ligand Exchange–Cathodic Stripping Voltammetry (CLE–CSV), stabilised dissolved Fe complexes were detected within the dissolved Fe fraction on the edges of one non-buoyant hydrothermal plume with observed ligand concentrations high enough to account for stabilisation of 4% of the total Fe emitted from the 5° S vent sites. If these results were representative of all hydrothermal systems, submarine venting could provide 12–22% of the global deep-ocean dissolved Fe budget.

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关键词：

Theoretical or Mathematical/ iron oceanography seafloor phenomena/ dissolved iron distribution dissolved iron stabilisation deep-sea hydrothermal plumes Mid-Atlantic Ridge hydrothermal venting iron concentrations CTD stations dissolved iron speciation plume dilution organic iron complexes iron colloids Competitive Ligand Exchange-Cafhodic Stripping Voltammetry ligand concentrations hydrothermal systems submarine venting global deep-ocean dissolved iron budget Fe/ A9220C Chemistry of the oceans A9150E Seafloor processes/ Fe/el