Biogeochemical data during POLARSTERN cruise PS106/1 (ARK-XXXI/1.1)

The methane (CH4) concentration and stable carbon isotopic signature of CH4 were measured in different Arctic sea ice types as well as in seawater underneath the ice floe during the Polarstern expedition PS106.1. Nutrient concentrations were measured only in sea ice. The ice drift took place between 4 - 15 June 2017, north of Svalbard (Macke and Flores, 2018). Sea ice cores were collected using a Kovacs Mark II 9cm drill ice corer. In all ice stations, the first ice core was used for in situ ice temperature measurements, and the second one for CH4 concentrations, stable carbon isotopic signature of CH4, bulk ice salinity and nutrient concentrations (Verdugo et al., 2021). Seawater samples were collected using a shipboard Sea-Bird Scientific SBE 911plus CTD (conductivity–temperature– depth) profiler equipped with ancillary sensors and integrated with a SBE32 CarouselWater Sampler with 24 Niskin bottles of 12L each (Macke and Flores, 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., 2021). Unfiltered nutrient samples were stored at -20°C, and analyzed for nitrate+nitrite, phosphate, nitrite, and silicate on a four-channel SEAL Analytical nutrient AutoAnalyser 3.