1 file.-- This dataset compiles information obtained during the cruise BOCATS 2016, This dataset gathers discrete measurements of CO2 (pH and alkalinity) and hydrographic variables (salinity, temperature, dissolved oxygen, nitrate, phosphate and silicate) obtained during the cruise BOCATS carried out along the OVIDE section from 17 June to 31 July 2016.
pH was measured spectrophotometrically following the Clayton and Byrne (1993). This method consists on adding a dye solution to the seawater sample, so that the ratio between two absorbances at two different wavelengths is proportional to the sample pH.
Alkalinity was measured using an automatic potentiometric titrator Titrando 809 Metrohm, with a Metrohm 6.0232.100 combination glass electrode and a Pt-1000 probe for temperature measurement following the methodology given by Pérez and Fraga (1987).
Dissolved oxygen was analyzed following the widely applied Winkler method.
Determinations of nitrate, phosphate and silicate were carried out following methods described by Hansen and Grassoff (1983)
Salinity and Temperature were recorded with a CTD probe, BOCATS (CTM2013-41048-P), Peer reviewed

This dataset reports for the classical rosette bottle data for the following Essential Ocean Variables: salinity, dissolved oxygen, total alkalinity, pH, nitrates and silicic acid. It also reports on the measurements of the CTD-O2 probe at the bottle levels: pressure, temperature, salinity and dissolved oxygen, The GEOVIDE cruise was carried out coast to coast between Portugal and Newfoundland via the south tip of Greenland, following the OVIDE line in the eastern part and crossing the Labrador Sea in the western part. The classical hydrographic rosette was cast 163 times at 78 different geographical positions called stations. While the CTD-O2 probe acquired continuous profiles of the “physical” variables (pressure, temperature, salinity and dissolved oxygen), 22 Niskin bottles were closed at different levels during the upcast to provide samples for biogeochemical analysis. After calibration, we find precisions for pressure, temperature, salinity and dissolved oxygen that fit the GO-SHIP international quality requirements. In parallel, but not simultaneously, a trace-metal rosette (TMR) was cast 53 times, also acquiring profiles of physical variables, and equipped with 24 Go-Flo bottles adapted for the sampling of trace metals. Depending on the number of operations, stations were identified as “Short” (one single CTD cast), “Large” (3 CTD casts), “XLarge” (up to 6) and “Super” (up to 11). All along the track of the ship, current magnitude and direction was measured by Ship Acoustic Doppler Current Profilers, down to 1000m depth, Spanish Ministry of Economy and Competitiveness through the BOCATS (CTM2013-41048-P) project, co-funded by the Fondo Europeo de Desarrollo Regional 2014–2020 (FEDER). CNRS and the AtlantOS H2020 project under grant number 633211. LABEX-Mer (French Government “Investissement d’Avenir” programme, ANR-10-LABX-19-01), No

1 file, LOCEAN has been in charge of analyzing the isotopic composition of the dissolved inorganic carbon (DIC) in sea water collected during a series of cruises or ships of opportunity mostly in the southern Indian Ocean , the North Atlantic, and the equatorial Atlantic, but also in the Mediterranean Sea and in the equatorial Pacific.

The LOCEAN sea-water samples for δ13CDIC were collected in 125/25 ml glass bottles until 2022/since then and poisoned with HgCl2 (1 ml of saturated solution) before storage in a dark room à 4°C until their measurement. The DIC was extracted from the seawater by acidification with phosphoric acid (H3PO4 85%) and CO2 gas that was produced was collected in a vacuum system following the procedure described by Kroopnick (1974). The isotopic composition of CO2 was determined using a dual inlet-isotopic ratio mass spectrometer (SIRA9-VG) by comparing the 13C/12C ratio of the sample to the 13C/12C ratio of a reference material, the Vienna-Pee Dee Belemnite (V-PDB). The isotopic composition is expressed in the δ-unit defined by Craig (1957)(method type 2). Experience showed that samples older than 3-4 years are likely to have experienced conservation issues and have been dismissed. The mass spectrometer has worked very well until 2014-2015. Afterwards, its aging as well as the aging of the preparation line resulted in more data loss, and often less accurate results. The preparation line was renovated in 2019, and analyses in 2020 were run manually, often repeating the measurement a second time for each sample.

Up to 2007-2008, δ13CDIC values have a precision of±0.01 ‰ (Vangriesheim et al.,2009) and a reproducibility of±0.02 ‰. After an interlaboratory comparison exercise led by Claire Normandeau (Dalhousie University), results suggest that recent LOCEAN samples have a slightly poorer reproducibility (±0.04 ‰ ) as well as an offset of -0.13‰ (details available in Reverdin et al., ESSD 2018) that is confirmed by Becker et al. 2016 work by comparison with other cruises after removing the anthropogenic signal. Recent comparisons in early May 2021 with Orsay GEOPS facility samples suggest that the current offset is much smaller and might be +0.03‰.

LOCEAN has installed in 2021 a new measurement device by coupling a Picarro G2131-I cavity ring down spectrometer (CRDS) with a CO2 extractor (Apollo SciTech) that will measure at the same time DIC (method type 3) (Leseurre, 2022). Since then, all water samples have been analyzed on this device.

Part of the data set, as well as a scientific context and publications are also presented on the WEB site https://www.locean-ipsl.upmc.fr/oceans13c

Individual files correspond to regional subsets of the whole dataset. The file names are based on two letters for the region followed by (-) the cruise or project name (see below) followed by –DICisotopes, followed by either -s (surface data) or -b (subsurface data), and a version number (-V0, …): example SI-OISO-DICisotopes-s-V0; the highest version number corresponds to the latest update of the cruise/project data set, and can be directly downloaded. Earlier versions can be obtained on request, but are not recommended, Support by OSU ECCE Terra, by LOCEAN, and by various French national institutes and programs is gratefully acknowledged (including INSU/CNRS, IFREMER, IRD, IPEV, LEFE program, ANR GEOVIDE, IPSL), as well as support of different French ‘Services nationaux d’Observation’, such as PIRATA, SSS and OISO/CARAUS. Many of the data originate from cruises on French Research vessels: R.V. Noroit, Suroit, Thalassa, Atalante, Marion Dufresne 2. Some data were collected during research cruises on non-French vessels, such as BOCATS in 2016 on the Spanish R/V Sarmiento de Gamboa. The SURATLANT data were collected on merchant vessels with support of EIMSKIP in Iceland., Peer reviewed