Iron(II) measurements on water column samples collected on the SIPEX II voyage of the Aurora Australis, 2012

Samples were then drawn through C-Flex tubing (Cole Parmer) and filtered in-line through 0.2 micron pore-size acid-washed capsules (Pall Supor membrane, Acropak 200). Regular sampling depths were as follows: 1000m, 750m, 500m, 300m, 200m, 150m, 125m, 100m, 75m, 50m, 30m, 15m. Samples were analysed within a minute of filtration.

Iron(II) was detected with the luminol method combining the experimental set-up of Hansard et al. (2009) with the chemistry as described by Croot and Laan (2002). Samples were not acidified prior to analysis and were pumped directly into the flow cell without an injection valve. Care was taken to maintain a stable light field during measurements as the luminol reagent was found to be extremely sensitive to changes in light intensity.

Photons from the reaction of luminol with iron(II) were counted with a Hamamatsu photomultiplier tube housed in a light-tight box. The signal was recorded using FloZ software (GlobalFIA) and the data for each run is stored in a separate file. There is a folder for each profile that contains all the files (automatically generated by the software), which are numbered.

The file numbers (e.g. sample1, sample2,...) correspond to the runs as noted in the lab book (see scans). P.L. Croot, P. Laan (2002). Analytica Chimica Acta 466: 261-273.

S.P. Hansard et al. (2009). Deep-Sea Res. I 56: 1117-1129.