Variability of the marine CO2 system, dissolved inorganic nutrients and stable oxygen isotopic ratio (δ18O) in Kaldfjorden in northern Norway from 2016 to 2018

• Main Author: Chierici, Melissa
• Format: Dataset
• Language: unknown
• Published: Institute of Marine Research 2020
• Subjects: Bergen; Norway; Scripps; Tromsø; Northern Norway; Ocean acidification
• Online Access: https://dx.doi.org/10.21335/nmdc-646962623; http://metadata.nmdc.no/metadata-api/landingpage/f42d4e2519862ef7ecd41c2f9f545053

Marine CO2 system data, total alkalinity (AT) and total dissolved inorganic carbon (CT) were collected from the full water column in Kaldfjorden at 3 stations, one per transect (inner, middle, outer) across the fjord. Sampling was performed quasi-monthly between September 2017 and September 2018. Additional sporadic sampling was carried out from September 2016 to September 2017. The seawater samples were collected from a handheld Niskin bottle (smaller vessels) and CTD-Rosette system (larger vessels) following standard procedures and analyzed at Institute of Marine Research (IMR), Tromsø, Norway after the sampling events following the method described in Dickson et al. (2007). CT was determined using gas extraction of acidified samples followed by coulometric titration and photometric detection using a Versatile Instrument for the Determination of Titration carbonate (VINDTA 3D, Marianda, Germany). AT was determined by potentiometric titration with 0.1 N hydrochloric acid using a Versatile Instrument for the Determination of Titration Alkalinity (VINDTA 3S, Marianda, Germany). Routine analyses of Certified Reference Materials (CRM, provided by A. G. Dickson, Scripps Institution of Oceanography, United States) ensured the accuracy of the measurements, which was better than ±2 µmol kg-1 for CT and AT. Description of the analytical methods can be found as a summary in the data file, as well as in the submitted manuscript Jones et al. 2020. Water samples for analysis of major nutrients (NO2, NO3, Si(OH)4, PO4) were preserved with 250 µL chloroform until post-cruise analysis following standard methods (Grasshoff et al., 2009) at the chemical laboratory at IMR, Bergen. Three replicates were analyzed for each sample. Samples for determination of the ratio of the stable oxygen isotope of seawater (δ18O) were transferred into 20 mL vials and stored in the dark at 4 °C until analysis using a Thermo Fisher Scientific Delta V Advantage mass spectrometer with Gasbench II. Data were standardised relative to Vienna Standard Mean Ocean Water (VSMOW) for δ18O (‰) with a reproducibility of replicate analyses of ±0.04‰. This study is a contribution to the project "Impact of massive Winter Herring Abundances on the KaLdfjorden Environment (WHALE; grant number 201914747042018), which was funded by the flagship "Effects of climate change on sea and coastal ecology in the north" and the flagship “Ocean acidification and effects in northern waters” of the FRAM - High North Research Centre for Climate and the Environment.