Sediment property data (0-6 cm) from the Nansen Legacy Joint Cruise 3 - Winter gaps cruise 2022702 (JC3)

The dataset includes water content, total nitrogen (TN), total carbon (TC), total organic carbon (TOC), total inorganic carbon (TIC), and carbon and nitrogen isotopic signatures (d13C, d15N) in marine sediments. Samples were collected during the Nansen Legacy Joint Cruise 3 - Winter gaps cruise in February in the northern Barents Sea; cruise 2022702 (JC3). Short sediment cores were subsampled from three replicate deployments of a giant box corer at stations P5, P7, slope500 and slope1500. At P1, only two deployments were completed. The sediment cores were sliced into 1cm-layers (0 - 6 cm) and immediately stored at -20°C onboard. All samples were freeze-dried in the laboratory of the Department of Geosciences (University of Oslo). Subsequently, approximately 1g of homogenised, freeze-dried sediment from each core interval was ground for total carbon (TC), total organic carbon (TOC), total nitrogen (TN), and their stable carbon (δ13C) and nitrogen (δ15N) isotopic signature measures. Elemental analysis was undertaken with an Elemental Analyser - Isotope Ratio Mass Spectrometry (EA-IRMS; Iso - Analytical Ltd., UK). Prior to TOC and d13C analysis, inorganic carbon was removed from the sediments by acid treatment (1M HCl). The standards δ13CV-PDB (Vienna PeeDee Belemnite) and δ15NAIR (atmospheric N2) were used as references for the carbon and nitrogen isotope values, respectively. TIC content was calculated by subtracting TOC from TC. Grain size distributions, performed on non-acidified samples, were determined using a Beckman Coulter LS 13320 Particle Size Analyser at the Department of Geoscience, University of Tromsø. Organic matter was removed with 10 % H2O2 and deflocculated with a 5 % Calgon solution (sodium hexametaphosphate and sodium carbonate) prior to analysis. Particles within the range of 0.04 – 2000μm were determined. Three replicate measurements were performed per sample, of which the average values are presented in the dataset. Grain size analysis was not performed for station P1.