Dataset: biogenic silica

Appropriate information on blanks and linear regressions of the standard curves is included within the original spreadsheet. A field blank value of 0.013 was subtracted for each measurement. The slope of the standard silicate curve was approximately 0.011 with an r-squared value of >0.99.

Original data as Excel spreadsheets:

CORSACS 1 Biogenic silica (XLS)
CORSACS 2 Biogenic silica (XLS)

BCO-DMO processing:

Biogenic Silica data were contributed in Microsoft Office Excel Spreadsheets -- one for each deployment (NBP0601 and NBP0608.) Both data sets reported sample depth, volume filtered, and Biogenic Silica in micromoles per liter, along with linear regressions of the standard curves used in the analysis. The spreadsheets were manually edited for upload to the BCO-DMO database. Neither data set included position information. As submitted, the original data lacked lat and lon and 0608 lacked date_local.  These columns were added by BCO-DMO as follows: lat and lon values are from hydro station metadata and date_local for NBP0608 was also taken from the hydro data as reported in another data set from this research project.

NBP0601 processing notes:
For NBP0601, a station number, date, bottle number, and sample depth were reported for each sample. Position information was not included. In order to be sure that Biogenic Silica station numbers matched Hydro casts station numbers, plots of the common information were prepared.

Sample depths were plotted against station number for the hydrographic data with Biogenic silica station number and sample depths overlaid. The points matched up nicely, confirming that station numbers were the same, therefore geographic position and time, as submitted with the hydrographic data, could be assigned to Biogenic Silica samples. (see comparison plot PDF file)

It should be noted that station+date_local for NBP0601 did not always match the hydro data. 21 of the 61 NBP0601 BioSi stations had a different date_local than the hydro stas; in every case, the BioSi sta number was 1 day ahead (e.g. station 18 hydro date = 12/30 and BioSi = 12/31)

The CTD/hydro data clearly stated that date was local, however if hydro date was in fact GMT then local time (GMT +13 for this timezone in December) would be 13 hours later (often one day ahead); if NBP0601 hydro data had date in GMT, and BioSi used local date, then the 1 day date offset could be explained. However, we have been unable to confirm this theory. Note that this means it is possible that the date_local column now has a mix of time zones; NBP0601 has original BioSi dates which might be local and NBP0608 has 'date' from hydro (called date_local) but might really be GMT.

NBP0608 processing notes:
For NBP0608, samples were identified using CTD cast number and depth. Position and time information were not reported. In order to be sure that Biogenic Silica station numbers matched the hydrographic station numbers, plots of the common information in both datasets were prepared. (see comparison plot PDF file)

Sample depths were plotted against station number for the hydrographic data with Biogenic silica station number and sample depths overlaid. The points matched up nicely, confirming that station numbers were the same, therefore geographic position and time, as submitted with the hydrographic data, could be assigned to Biogenic Silica samples.