READ ME File For 'Datasets in support of the thesis ‘Stable carbon isotopes from the Eastern Atlantic Ocean: anthropogenic and biological signals’'.

Dataset DOI: https://doi.org/10.5258/SOTON/D2903

ReadMe Author: KOKUHENNADIGE HASHAN NIROSHANA, University of Southampton ORCID ID 0000-0002-7679-114X

This dataset supports the thesis entitled "Stable carbon isotopes from the Eastern Atlantic Ocean: anthropogenic and biological signals"
AWARDED BY: Univeristy of Southampton
DATE OF AWARD: 2023

DESCRIPTION OF THE DATA

These datasets contain stable carbon isotopic composition of dissolved inorganic carbon (δ13CDIC) and particulate organic carbon (δ13CPOC) for the Eastern Atlantic Ocean. These include three datasets: Dataset_BUS, Dataset_PAP and Dataset_NEA.

1. Dataset_BUS: Stable carbon isotopic composition of dissolved inorganic carbon (δ13CDIC), DIC and nutrients in the coastal waters of the Benguela Upwelling System in the southeast Atlantic Ocean during the GEOTRACES cruise GA08 in the summer (November - December) of 2015.

This dataset contains two tables: Table 1 and Table 2.

Table 1 provides the geographical positions of the sampling stations examined in the coastal waters along the southwestern coast of Africa during the GEOTRACES cruise GA08 in the summer (November - December) of 2015.

Table 2 contains measurements of δ13CDIC, DIC, nutrients and hydrographic parameters from the upper 200 m waters of the sampling stations examined in the Benguela Upwelling System in the southeast Atlantic Ocean (from 3ᵒS to 28.67ᵒS along the southwestern coast of Africa). Samples were collected onboard the RV Meteor M121 during the GEOTRACES cruise GA08 from 22.11.2015 to 27.12.2015. Samples for DIC and δ13CDIC were collected directly from the Niskin bottles via silicone tubing into 250 mL Schott Duran borosilicate glass bottles, following the established best-practice protocols of Dickson et al. (2007) and McNichol et al. (2010). The sample bottles were rinsed with excess sample by overflowing with seawater and filled without any air bubbles. An air headspace (1% of the bottle volume, 2.5 mL) was introduced and 50 µL of saturated mercuric chloride (HgCl2) solution was added to each bottle before sealing air-tight with greased (Apiezon® L grease) ground glass stoppers, duct tape and plastic clamps. The samples were stored in the dark at 4 ᵒC until analysis. δ13CDIC in samples was measured following the best-practice procedures of Torres et al. (2005) and Humphreys et al. (2016). δ13CDIC measurements were determined using a Thermo Scientific Delta V Advantage Continuous Flow Isotope Ratio Mass Spectrometer connected to a Thermo Scientific GasBench II system and a CTC Analytics PAL Autosampler, at the National Oceanography Centre, Southampton, UK from October to November 2019. The precision (±1σ standard deviation) reported for δ13CDIC was close to ±0.02 ‰. DIC measurements were carried out by coulometric titration using a VINDTA 3C system (Versatile Instrument for the Determination of Total inorganic carbon and titration Alkalinity, Marianda, Kiel, Germany) or by infrared detection using a DIC Analyzer AS-C3 (Apollo SciTech, USA) at the University of Southampton, UK from April to July 2016. DIC analyses were calibrated using certified reference materials (Batch numbers 146, 148, 151, 152 and 154 provided by Andrew. G Dickson, Scripps Institution of Oceanography, USA). A precision (±1σ standard deviation) of ±3.7 μmol kg-1 was reported for DIC based on repeat analyses of certified reference materials. Charlotte Miskin-Hymas, Matthew Humphreys and Eric Achterberg contributed to DIC measurements, and J.P. Baro and J.C. Yong contributed to dissolved nutrient measurements and provided these data. Moreover, this dataset contains data of few calculated variables: apparent oxygen utilization (AOU), preformed δ13CDIC (δ13C0), phosphate normalised δ13CDIC (δ13CDICNorm).

2. Dataset_PAP: Stable carbon isotopic composition of particulate organic carbon (δ13CPOC), dissolved inorganic carbon (δ13CDIC) and of the sedimentary organic carbon in the surface sediments, POC, DIC and chlorophyll a at the Porcupine Abyssal Plain (PAP) site in the northeast Atlantic Ocean during the DY130 cruise in the spring (March - April) of 2021.

This dataset contains three tables: Table 1, Table 2, and Table 3.

Table 1 provides the geographical positions of the sampling stations examined for δ13CPOC and δ13CDIC at the Porcupine Abyssal Plain (PAP) site in the northeast Atlantic Ocean during the DY130 cruise in the spring (March - April) of 2021.

Table 2 contains measurements of POC, DIC, δ13CPOC, δ13CDIC, chlorophyll a (Chl-a) and hydrographic parameters in the water column of the sampling stations examined at the PAP site in the northeast Atlantic Ocean (49ᵒN, 16.5ᵒW). Samples were collected onboard the RRS Discovery during the DY130 cruise from 25.03.2021 to 14.04.2021. Samples for POC and δ13CPOC of suspended particulate organic matter were collected directly from the Niskin bottles into 2 L polycarbonate bottles and then filtered (about 1-2 L) onboard through 25 mm pre-combusted glass fiber filters (Whatman GF/F) under low vacuum condition. The filters were rinsed with Milli-Q water, then folded and wrapped in pre-baked aluminium foil pouches and stored in a freezer at -80 ᵒC onboard until analyses ashore. POC and δ13CPOC in samples were measured following the protocols of Brown et al. (2014) and Ye et al. (2017) and determined using a Thermo Scientific Delta V Advantage Isotope Ratio Mass Spectrometer (IRMS) coupled with an elemental analyzer (Flash 2000 CHNS-O, Thermo Scientific) via Thermo Scientific ConFlo IV interface device at the National Oceanography Centre, Southampton, UK from November 2021 to February 2022. The precision (±1σ standard deviation) of the instrument was better than ±2% for POC and ±0.1 ‰ for δ13CPOC.
Samples for DIC and δ13CDIC were collected directly from the Niskin bottles via silicone tubing into 250 mL borosilicate glass bottles and 40 mL clean borosilicate glass vials, respectively following the best-practice protocols of Dickson et al. (2007) and McNichol et al. (2010). The sample bottles and vials were rinsed with excess sample by overflowing with seawater and filled without any air bubbles. An air headspace (1% of the bottle volume) was introduced to 250 mL borosilicate glass bottles before sealing air-tight with greased (Apiezon® L grease) ground glass stoppers and duct tape. However, 40 mL glass vials were fully filled with seawater without giving any air headspace before sealing air-tight with plastic screw caps and secured with parafilm. Samples were immediately preserved with saturated mercuric chloride (HgCl2) solution (0.02% of the sample container volume) and stored in the dark at 4 ᵒC until analysis. δ13CDIC in samples was measured following the best-practice procedures of Torres et al. (2005) and Humphreys et al. (2016). δ13CDIC measurements were determined using a Thermo Scientific Delta V Advantage Continuous Flow Isotope Ratio Mass Spectrometer connected to a Thermo Scientific GasBench II system and a CTC Analytics PAL Autosampler, at the National Oceanography Centre, Southampton, UK from August to September 2021. The precision (±1σ standard deviation) reported for δ13CDIC was better than ±0.02 ‰. DIC measurements were carried out by coulometrically using a MARIANDA VINDTA 3C system (Versatile Instrument for the Determination of Total inorganic carbon and titration Alkalinity, Marianda, Kiel, Germany) at the National Oceanography Centre, Southampton, UK. DIC analyses were calibrated using certified reference materials (Batch numbers 180 and 191 provided by Andrew. G Dickson, Scripps Institution of Oceanography, USA). A mean accuracy of -0.54 μmol kg-1 (n=37) was reported for DIC based on repeat analyses of certified reference materials. Anita Flohr contributed to DIC measurements and Corinne Pebody contributed to chlorophyll a measurements and provided these data. Moreover, this dataset contains data of few calculated variables: POC/Chl-a ratios and [CO2(aq)].

Table 3 contains measurements of δ13C of the sedimentary organic carbon in the surface sediments collected at the PAP site in the northeast Atlantic Ocean (49ᵒN, 16.5ᵒW)  during the DY130 cruise in the spring (March - April) of 2021. Surface sediment (0-2 cm) samples were collected by using NOC-NMFS Bowers & Connelly megacorer (containing 10 core tubes with 10 cm diameter). Once cores were recovered, the sediment samples were transferred into plastic bags using stainless steel spatula and stored at -80 ᵒC onboard until analysis. δ13C in treated sediment samples was analysed using the IRMS instrument the National Oceanography Centre, Southampton, UK in March 2022.

3. Dataset_NEA: Stable carbon isotopic composition of dissolved inorganic carbon (δ13CDIC) and particulate organic carbon (δ13CPOC), DIC, POC and phosphate in the subtropical gyre region of the northeast Atlantic Ocean during the SO279 cruise in the winter (December 2020 - January 2021) of 2020. 

This dataset contains three tables: Table 1, Table 2, and Table 3.

Table 1 provides the geographical positions of the sampling stations examined in the subtropical gyre region of the northeast Atlantic Ocean during the SO279 cruise in the winter (December 2020 - January 2021) of 2020.

Table 2 contains measurements of δ13CDIC, DIC, phosphate and hydrographic parameters in the water column of the sampling stations examined in the subtropical gyre region of the northeast Atlantic Ocean (31-35ᵒN, 25-34.6ᵒW). Samples were collected onboard the RV Sonne during the SO279 cruise from 04.12.2020 to 05.01.2021. Samples for DIC and δ13CDIC were collected directly from the Niskin bottles via silicone tubing into 250 mL borosilicate glass bottles and 40 mL clean borosilicate glass vials, respectively following the best-practice protocols of Dickson et al. (2007) and McNichol et al. (2010). The sample bottles and vials were rinsed with excess sample by overflowing with seawater and filled without any air bubbles. An air headspace (1% of the bottle volume) was introduced to 250 mL borosilicate glass bottles before sealing air-tight with greased (Apiezon® L grease) ground glass stoppers and duct tape. However, 40 mL glass vials were fully filled with seawater without giving any air headspace before sealing air-tight with plastic screw caps and secured with parafilm. Samples were immediately preserved with saturated mercuric chloride (HgCl2) solution (0.02% of the sample container volume) and stored in the dark at 4 ᵒC until analysis. δ13CDIC in samples was measured following the best-practice procedures of Torres et al. (2005) and Humphreys et al. (2016). δ13CDIC measurements were determined using a Thermo Scientific Delta V Advantage Continuous Flow Isotope Ratio Mass Spectrometer connected to a Thermo Scientific GasBench II system and a CTC Analytics PAL Autosampler, at the National Oceanography Centre, Southampton, UK from August to September 2021. The precision (±1σ standard deviation) reported for δ13CDIC was better than ±0.02 ‰. DIC measurements were carried out by coulometrically using a MARIANDA VINDTA 3C system (Versatile Instrument for the Determination of Total inorganic carbon and titration Alkalinity, Marianda, Kiel, Germany) at the Royal Netherlands Institute for Sea Research (NIOZ), Netherlands. DIC analyses were calibrated using certified reference materials (Batch numbers 189 provided by Andrew. G Dickson, Scripps Institution of Oceanography, USA). A precision (±1σ standard deviation) of ±2 μmol kg-1 was reported for DIC based on repeat analyses of certified reference materials. Louise Delaigue contributed to DIC and phosphate measurements and provided these data. Moreover, this dataset contains data of few calculated variables: δ13Cbio (biological effect on δ13CDIC) and δ13Cas (air-sea exchange signature of δ13C).

Table 3 contains measurements of δ13CPOC and POC in the water column of the sampling stations examined in the subtropical gyre region of the northeast Atlantic Ocean (31-35ᵒN, 25-34.6ᵒW) during the SO279 cruise in the winter (December 2020 - January 2021) of 2020. Samples for POC and δ13CPOC measurements were collected from the depths of 25, 50, 75, 120-150 and 300 m, onto 293 mm pre-combusted glass fiber filters (Whatman GF/B) by filtering about 700-1900 L of seawater using in situ Stand-Alone Pumps (SAPs; Challenger Oceanics). The filters were rinsed with Milli-Q water, then folded and wrapped in pre-baked aluminium foil pouches and stored in a freezer at -80 ᵒC onboard until analyses ashore. POC and δ13CPOC in samples were measured following the protocols of Brown et al. (2014) and Ye et al. (2017) and determined using a Thermo Scientific Delta V Advantage Isotope Ratio Mass Spectrometer coupled with an elemental analyzer (Flash 2000 CHNS-O, Thermo Scientific) via Thermo Scientific ConFlo IV interface device at the National Oceanography Centre, Southampton, UK in February 2022. The precision (±1σ standard deviation) of the instrument was better than ±2% for POC and ±0.1 ‰ for δ13CPOC. 

This dataset contains:
Three datasets: Dataset_BUS, Dataset_PAP and Dataset_NEA.

1. Dataset_BUS contains two tables: Table 1 and Table 2.

Table 1 provides the geographical positions of the sampling stations examined in the coastal waters along the southwestern coast of Africa during the GEOTRACES cruise GA08 in the summer (November - December) of 2015.

Table 2 contains measurements of δ13CDIC, DIC, nutrients and hydrographic parameters from the upper 200 m waters of the sampling stations examined in the Benguela Upwelling System in the southeast Atlantic Ocean (from 3ᵒS to 28.67ᵒS along the southwestern coast of Africa) during the GEOTRACES cruise GA08 in the summer (November - December) of 2015.

2. Dataset_PAP contains three tables: Table 1, Table 2, and Table 3.

Table 1 provides the geographical positions of the sampling stations examined for δ13CPOC and δ13CDIC at the Porcupine Abyssal Plain (PAP) site in the northeast Atlantic Ocean during the DY130 cruise in the spring (March - April) of 2021.

Table 2 contains measurements of POC, DIC, δ13CPOC, δ13CDIC, chlorophyll a (Chl-a) and hydrographic parameters in the water column of the sampling stations examined at the PAP site in the northeast Atlantic Ocean (49ᵒN, 16.5ᵒW) during the DY130 cruise in the spring (March - April) of 2021. 

Table 3 contains measurements of δ13C of the sedimentary organic carbon in the surface sediments collected at the PAP site in the northeast Atlantic Ocean (49ᵒN, 16.5ᵒW) during the DY130 cruise in the spring (March - April) of 2021. 

3. Dataset_NEA contains three tables: Table 1, Table 2, and Table 3.

Table 1 provides the geographical positions of the sampling stations examined in the subtropical gyre region of the northeast Atlantic Ocean during the SO279 cruise in the winter (December 2020 - January 2021) of 2020. 

Table 2 contains measurements of δ13CDIC, DIC, phosphate and hydrographic parameters in the water column of the sampling stations examined in the subtropical gyre region of the northeast Atlantic Ocean (31-35ᵒN, 25-34.6ᵒW) during the SO279 cruise in the winter (December 2020 - January 2021) of 2020. 

Table 3 contains measurements of δ13CPOC and POC in the water column of the sampling stations examined in the subtropical gyre region of the northeast Atlantic Ocean (31-35ᵒN, 25-34.6ᵒW) during the SO279 cruise in the winter (December 2020 - January 2021) of 2020. 

Date of data collection:
1. Dataset_BUS: collected from 22.11.2015 to 27.12.2015.
2. Dataset_PAP: collected from 25.03.2021 to 14.04.2021.
3. Dataset_NEA: collected from 04.12.2020 to 05.01.2021.

Information about geographic location of data collection: 
1. Dataset_BUS: collected in the Benguela Upwelling System in the southeast Atlantic Ocean (from 3ᵒS to 28.67ᵒS along the southwestern coast of Africa).
2. Dataset_PAP: collected at the PAP site in the northeast Atlantic Ocean (49ᵒN, 16.5ᵒW).
3. Dataset_NEA: collected in the subtropical gyre region of the northeast Atlantic Ocean (31-35ᵒN, 25-34.6ᵒW). 

Funders: 
Commonwealth Scholarship Commission in the United Kingdom

Related projects:
Subproject 518476102 OES-RTSG 18-19 Kokuhennadige-Whiteside

Date that the file was created: March, 2023

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