Biogenic silicate concentration in sea water samples, collected from the underway supply in the Southern Ocean during the austral summer of 2016/2017, on board the Antarctic Circumnavigation Expedition.

***** Dataset abstract *****
 
Biogenic Silicate (Bsi) concentration (µmol/L) in seawater data. Water samples were collected from the underway seawater supply, filtered on board and then analysed by flow injection following appropriate digestion.

This data supports chemical and biological oceanography studies conducted during the Antarctic Circumnavigation Expedition.

***** Original sample collection *****

Samples were collected from the underway seawater line in duplicate, using unpowdered latex gloves. Before sampling the 2 L polycarbonate bottle and cap were rinsed three times with seawater. A known volume (0.5-2 L) of each samples was filtered on 0.8 µm 25 mm CAMembrane under gentle vacuum and stored in petri dishes. Samples from each station were gathered in a labelled ziplock bag in the ship’s -20 degrees C walk-in freezer. At the Alfred Wegener Institute, biogenic silica was digested in 0.2 N NaOH at 95 °C for 45 minutes. Once cold, the pH was neutralized with 1 N HCl. 

***** Data Analysis *****

Analyses were carried out in February to April 2018 using a QuAAtro Seal Analytical autoanalyser, following Seal Analytical method (Method No. Q-066-05 Rev. 3). The calibration is based on Certipur Standard Solution: Certipur, traceable to Standard Reference Material (SRM) from NIST SiO2 in NaOH 0,5 mol/l, 1000 mg/L, Merck. Based on this standard, a five point calibration curve was prepared and measured in duplicates, r2 was > 0.999. Biogenic silica in situ concentrations were calculated using digestion and seawater filtration volumes as well as procedural blanks. Limit of detection yielded 0.07 micro-mol/L for silicate.

***** Quality checking *****

At sea, procedural blanks using ultrapure water for filtration were collected. Analysis showed average procedural blanks of 0.013 +/- 0.004 µmol/L (n=10). Procedural blank were subtracted to measured biogenic silica in the digestion extracts. Note that blanks were much lower than measured concentrations in digestion extracts (7.1-1510 µmol/L). Along each set of analysis, two Certipur solutions of 20.72 and 41.45 µmol/L nominal concentrations were analysed. The measured concentrations were 21.9 +/- 1.2 and 42.0 +/- 0.5 µmol/L, respectively (n=19).

***** Dataset contents *****

- ace_biogenic_silicate_concentration_in_seawater_underway.csv, data, comma-separated values
- ace_biogenic_silicate_concentration_in_seawater_underway_visual_summary.png, metadata, portable network graphics
- data_file_header.txt, metadata, text format
- README.txt, metadata, text format

***** Dataset contact *****

Christel Hassler, University of Geneva, Switzerland. ORCID: 0000-0002-8976-5469 christel.hassler@unige.ch

***** Dataset license *****

This biogenic silicate dataset is made available under the Creative Commons Attribution 4.0 International License (CC BY 4.0) whose full text can be found at https://creativecommons.org/licenses/by/4.0/

***** Dataset citation *****

This dataset can be cited as: 
Hassler, C. & Ellwood, M. (2021). Biogenic silicate concentration in sea water samples, collected from the underway supply in the Southern Ocean during the austral summer of 2016/2017, on board the Antarctic Circumnavigation Expedition. (1.0) [Data set]. Zenodo. https://doi.org/10.5281/zenodo.3249051