Stable isotope compositions (δ¹³C and δ¹⁵N) of seston measured on water bottle samples from CTD/Large volume Water-sampler-system during POLARSTERN cruise PS100 (ARK-XXX/2)

Seston samples collected with Niskin bottles; 2 L filtered onto precombusted 25mm (Ø) GF/F filters. δ¹³C and δ¹⁵N stable isotopes analyzed with elemental analyzer (Thermo Flash 2000) coupled to an isotope-ratio mass spectrometer (Thermo, Delta V Plus). Sample preparation for IRMS analysis (BSIA) were done according to the LIENSs SOPs. (see: https://lienss.univ-larochelle.fr/IMG/pdf/lienss_sif_appendix_2_protocols_v3-8.pdf)

Devices (LIENSs Stable Isotope Facility, La Rochelle, France): Elemental analyzer: Flash 2000, Thermo Scientific, Milan, Italy.

Isotope ratio mass spectrometer: Delta V Plus with a Conflo IV interface, Thermo Scientific, Bremen, Germany.

Reference materials for calibration: δ¹³C: USGS-24, IAEA-CH6, IAEA-600, USGS-61, USGS-62. δ¹⁵N: IAEA-N2, IAEA-NO-3, IAEA-600, USGS-61, USGS-62.

Working standards (two-point calibration): %C, %N, δ¹³C and δ¹⁵N: USGS-61 (Caffeine) and USGS-62 (Caffeine)

Analytical precision: δ¹³C: <0.10 ‰ (Thermo Scientific specifications). δ¹⁵N: <0.10 ‰ (Thermo Scientific specifications).

Results are expressed in the δ unit notation as deviations from standards (Vienna Pee Dee Belemnite for δ¹³C and N₂ in air for δ¹⁵N) following the formula: δ¹³C or δ¹⁵N = [(Rsample/Rstandard) - 1] x 10³, where R is ¹³C/¹²C or ¹⁵N/¹⁴N, respectively.