Stable isotopic signature of Dissolved Inorganic Carbon from surface underway samples collected during cruise AMT16
Originator's Protocol for Data Acquisition and Analysis
This data originates from analyses on samples collected from the ship's non-toxic supply each day at pre-dawn and the 11:00 hours CTD stations according to the cruise report. Seawater samples were collected in clean borosilicate glass containers via a flexible silicon tube and preserved with mercuric chloride.
Total inorganic carbon was analyzed by manometry.
The stable carbon isotope enrichment in inorganic carbon in the water column was analysed using acidification and mass spectrometry (see Quay, Tilbrook and Wong, 1992). Seawater samples were collected and stored in pre-washed, baked (450°C) ground glass-stoppered bottles and then poisoned with HgCl 2 . CO 2 was extracted from the seawater samples by drawing the seawater sample into a gravimetrically calibrated burette, acidifying with phosphoric acid and stripping with 99.999% pure He at a flow rate of 40cm 3 min -1 for 30 minutes and collecting the CO 2 at -196°C after trapping out water at -70°C (the helium stripping technique). The d13C of the CO 2 gas was measured on a Finnigan MAT 251 mass spectrometer.
References Cited
Quay, P.D., Tilbrook, B., Wong, C.S., 1992. Oceanic uptake of fossil fuel CO 2 : Carbon-13 evidence, Science , 256, 74-79.
Instrumentation Description
Not applicable for this data set.
BODC Data Processing Procedures
Data were submitted via email in an Excel spreadsheet archived under BODC's accession number UWA060487. The data file received contained underway DIC and d13C data for cruises AMT15, AMT16 and AMT17. Sample metadata (Date, time (GMT), latitude, longitude and depth) were checked against information held in the database. The sampling times had been converted to GMT from local time in the file provided by the data originator. Two discrepancies were noticed; the date of the sample taken on 29 May 2005 at 13.09 hours was incorrect when compared to the central navigation file and cruise report, so was changed to 28 May 2005. The date of the sample reported in the data file as 14 June 2004, 04.12 hours was changed to 14 June 2005 according to the cruise report. Four of the latitude, date and time combinations differed by a degree from the latitude at the sampling time in the central navigation file. Data were loaded against the position taken from this source.
The data were reformatted and marked up with BODC parameter codes and loaded into BODC's samples database under Oracle Relational Database Management System. The data contain three samples with replicate data. The average and standard deviation (SD) were loaded for the two samples obtained on 19 June 2005, 05.10 hours, lat: 33.35°, lon:-45.32°. The average and SD of the three samples taken on 22 June 2005, 04.10 hours, lat: 37.35°, lon:-33.66°, were loaded. Of the three samples taken on 26 June 2005, 04.43 hours, lat: 46.03°, lon:-19.67°, only the average and SD from two of the samples were loaded, as the third sample had no DIC data value and the d13C data value was flagged suspect.
The stable carbon isotope data were provided in parts per thousand (per mille) quoted relative to the Pee Dee Belemnite standard (PDB). The total dissolved inorganic carbon concentration data were provided in micro grams per kilogram. These units were consistent with the BODC parameter code units and no conversions were applied.
A parameter mapping table is provided below:
Originator's Parameter | Units | Description | BODC Parameter Code | Units | Comments |
---|---|---|---|---|---|
DIC Conc. (µmol/kg) | µmol/kg -1 | Concentration of carbon (total inorganic) {TCO2} per unit volume of the water body [dissolved plus reactive particulate phase] by manometry | TCO2MATX | µmol/l -1 | n/a |
Delta 13C (per mille PDB) | ‰ (PDB) | Enrichment of 13C in inorganic carbon in the water body [dissolved plus reactive particulate phase] by acidification and mass spectrometry | D13CMITX | ‰ (PDB) | n/a |
DIC Conc. (µmol/kg) standard deviation | µmol/kg -1 | Standard deviation of the concentration of carbon (total inorganic) {TCO2} per unit volume of the water body [dissolved plus reactive particulate phase] by manometry | TCO2CBSD | µmol/l -1 | n/a |
Delta 13C (per mille PDB) standard deviation | ‰ (PDB) | Standard deviation of the enrichment of 13C in inorganic carbon in the water body [dissolved plus reactive particulate phase] by acidification and mass spectrometry | SD13CMTX | ‰ (PDB) | n/a |
Data Quality Report
BODC was advised by the data originator of two quality issues with one sample in the data and these data points were flagged 'L' within the database.
Problem Report
Not relevant to this data set.