Biogeochemical data during RV POLARSTERN cruise PS109

The concentration and carbon isotope delta (δ13C) of methane (CH4), the water mass tracer δ18O(H2O), and nutrient concentrations were measured in seawater during the Polarstern expedition PS109. The expedition took place from 12 September to 14 October 2017, on the Northeast Greenland continental shelf. Seawater samples were collected using a shipboard Sea-Bird Scientific SBE911plus CTD (Conductivity-Temperature-Depth) profiler, integrated into a SBE32 Carousel Water Sampler with 24 Niskin bottles of 12 L each (Kanzow et al., 2018). The analysis of CH4 concentrations and carbon isotope delta, 13C, were done using a gas chromatograph (Agilent GC 7890B) with a Flame Ionization Detector (FID) and a Thermo Finnigan Delta plus XP mass spectrometer, respectively (Verdugo et al., 2022). The δ18O(H2O) samples were analyzed using a Finnigan MAT Delta S mass spectrometer with two equilibration units. Unfiltered nutrient samples were taken in 15 mL Falcon tubes at the same depth as CH4 concentrations and (δ13C) of CH4 samples, stored at -20°C, and were analyzed for nitrate+nitrite, phosphate, nitrite, and silicate on a four-channel SEAL Analytical nutrient AutoAnalyser 3.