Vertical Fe GoFlo measurements from R/V Tangaroa cruise 61TG_3052 in the Southern Ocean in 1999 (SOIREE project)

SOIREE Vertical Fe GoFlo Data<br><br>

During the cruise we had the following three objectives:<br>
(1) Undertake continuous sampling of the infused patch for dissolved/total iron<br>
(2) Obtain samples from vertical profiles, using Go-Flo bottles, to examine the<br>
partitioning between dissolved and particulate iron within the water column, both<br>
inside and outside the patch.<br>
(3) Undertake measurements to determine iron speciation within the water column.<br>
<br>
Go-Flo casts were taken both inside and outside the patch during the course<br>
of the experiment. Typically, water samples were obtained from four standard<br>
depths (20, 40, 60 and 80 m) throughout the water column at each station. Deeper<br>
samples (> 80 m) were obtained at some stations to examine the concentration of<br>
iron below the mixed layer. Both filtered (0.2 um) and unfiltered samples were<br>
collected. These samples will be analysed for Fe and other trace metals (Zn, Cd, Mn, Cu)<br>
back in the clean laboratory at the University of Otago.<br>
<br>
The speciation of iron was measured using competitive ligand exchange cathodic stripping<br>
voltammetry (CLE CSV) on samples from 40 m depth from stations both inside and outside the<br>
patch. This technique determines the total concentration of iron binding ligands present<br>
in the sample and their relative binding strengths. From the data generated an estimation<br>
of the inorganic iron concentration, Fe`, can also be made, this value can be used to<br>
approximate the amount of iron that may be available for uptake by the phytoplankton.<br>
<br>

<i><b>References</b><br>
Bowie, A.R., Maldonado, M.T., Frew, R.D., Croot P.L., Achterberg, E.A., Mantoura, R.F.C.,<br>
Worsfold, P.J., Law, C.S., Boyd P.W., The Fate of Added Iron during a Mesoscale Fertilisation<br>
Experiment in the Southern Ocean, Deep-Sea Research II (2001), SOIREE special issue, in the press.<br>
<br>
Bruland, K.W., Franks, R.P., Knauer, G.A., Martin, J.H., 1979. Sampling and analytical methods for<br>
the determination of copper, cadmium, zinc and nickel at the nanogram per litre level in seawater.<br>
Analytica Chimica Acta 105, 233-245.<br>
<br>
Danielsson, L.G., Magnusson, B., Westerlund, S., Zhang, K., 1982. Trace-metal determinations<br>
in estuarine waters by electrothermal atomic-absorption spectrometry after extraction of<br>
dithiocarbamate complexes into freon. Analytica Chimica Acta 144, 183-188.<br>
</i><br>