Water column data on dissolved inorganic nutrients (nitrite, nitrate, phosphate and silicic acid) from the Nansen and Amundsen Basins in the Arctic Ocean 2024 (AO2024) cruise, 2024007009, with R.V. Kronprins Haakon, 27 July - 10 August 2024

The cruise 2024007009 aboard the Research Vessel Kronprins Haakon covered the central Arctic Ocean as part of the project “Sustainable Development in the Arctic Ocean-SUDARCO” within the FRAM-High North Research Centre for Climate and the Environment and aims to establish a holistic understanding and of a changing marine Arctic climate and ecosystem and the societal impact. Details on the cruise is found in the cruise report (Dodd et al., 2024).

Water column temperature and salinity profiles were obtained with a conductivity-temperature-depth (CTD) sensor system Sea-Bird SBE 911+ mounted on a General Oceanics rosette sampler equipped with 24 Niskin bottles used for seawater sampling of chemical variables in the water column. Samples for the determination of dissolved inorganic nutrients were collected from the water column at a total of 46 stations in the Nansen and Amundsen basins, central Arctic Ocean. The seawater samples were collected from Niskin bottles in 20 ml plastic HDPE vials (rinsed three times) and preserved with 250 µL chloroform and stored +4°C and dark until post-cruise analysis of nitrite (NO2), nitrate (NO3-), phosphate (PO43-), and silicate (Si(OH)4), on an automated analysis (AA) system from Skalar Analytical B.V. (The Netherlands) at the chemical laboratory at Institute of Marine Research, Bergen, Norway. Methods followed standard colorimetric methods first described by Bendschneider & Robinson (1952) and Grasshof (1965) For specific methodological details see Gundersen et al., 2022. Three replicates were analyzed for each sample. The precision, based on triplicate analysis of each sample were: 0.06 µmol/L for NO2, 0.04 µmol/L for NO3-, 0.06 µmol/L for PO43- og 0.07 µmol/L for Si(OH)4 . The detection limits are 0.06 µmol/L, 0.5 µmol/L, 0.06 µmol/L and 0.7 µmol/L for NO2, NO3-, PO43-, and Si(OH)4, respectively. The study was funded by the Klima og Miljø Departementet (KLD) og Nærings-og Fiskeri Departementet (NFD) through the FRAM-High North Research Centre for Climate and the Environment.