Arctic deep-sea sediment pore-fluid concentrations of oxygen, ammonium, nitrate, and divalent manganese and iron

This dataset consists of depth profiles of pore-fluid chemistry from multiple sites along the Arctic mid-ocean ridge system. The primary goal of collecting these data was to compare them with microbial community profiles to investigate the coupling between microbial taxa and redox-sensitive chemical constituents. Sampling was conducted during several research cruises across different years and seasons, using consistent onboard methodologies. The cores were split in half, where on one side the oxygen data was measured using a micro-fiber optic oxygen transmitter (Microx TX3, PreSense). Concomitantly on the other half, pore-fluids were extracted using Rhizon CSS soil moisture sampler (Rhizosphere research products) at intervals of 5–30 cm. The upper 100 cm were sampled at finer intervals than deeper sections due to reduced pore-fluid availability caused by sediment compression. The pore-fluids were analyzed for cations and nutrients. The cation samples were acidified up to 3 vol% ultra pure HNO3 and stored at 4 degrees Celsius until analyses on the Thermo Scientific iCAP 7600 inductively coupled plasma optical emission spectrometer. The nutrient samples were frozen at -20 degrees Celsius until analyses on the Seal Analytical Quaatro at Earth Sciences department in the University of Bergen. The microbial community data (16S rRNA gene) is available on NCBI sequence database under project numbers: PRJNA784957, PRJEB102573, PRJNA529480, PRJNA789780. From one core the age was determined through 14C dating of planktonic foraminifera Neogloboquadrina pachyderma. The 14C was analysed at the Radiocarbon Dating Laboratory (Lunds Universitet, Sweden).