Dataset: GN01 Se Speciation

For dissolved samples: 0.45 µm Supor membrane filtered seawater samples from the GEOTRACES Carousel/GO-FLO bottles were placed into 1 L borosilicate glass bottles and acidified to pH < 2 by addition of 4 mL 6 M HCl. Samples were stored at room temperature in the dark.

Dissolved selenite, selenite+ selenite, and total dissolved selenium concentrations were determined in triplicate using selective hydride generation/atomic absorption spectrometry following Cutter (1978), Cutter (1983), and Cutter and Bruland (1984). The standard addition method of calibration was used to assure accuracy (one sample on an analysis day was used and its slope applied to the other samples on that day). Selenate was calculated as the difference between selenite+selenate and selenite determinations, while organic selenide was the difference between total dissolved selenium and selenite+selenate determinations. Precision was always less than 10% RSD, but typically less than 5% RSD at the observed concentrations. Detection limits were 0.02 nmol/L for all selenium species.