Physical oceanography, anthropogenic tracers and noble gases during Maria S. Merian cruise MSM73

The bottle data on cruise MSM73 contain measurements of pressure, temperature, salinity and oxygen (derived from CTD values at the location of closing bottles) and direct measurements of oxygen, CFC-12, SF6 and the noble gases helium and neon. The data were collected with the research vessel Maria S. Merian. Region: subpolar North Atlantic, 11°W-54°W, 44°N-61°N, Ports: Cadiz - St. John's, Date: April 06 - May 22, 2018. The bottle data were collected by an SBE 32 water sampler system in connection with a SBE 911 plus CTD. The CTD was mounted to a metal frame with 22 Niskin bottles of 10 l volume, which was lowered from the sea surface down to 10 m above the seafloor. Pressure, temperature, salinity and oxygen data from the CTD were recorded at the time when closing the bottles. In addition, direct samples of salinity and oxygen from the water bottles have been taken to calibrate the CTD data. The accuracy of the CTD measurements is: 1 dbar for pressure, 0.001 °C for temperature, 0.003 for salinity, 4.0 µmol/kg for oxygen. The oxygen samples from the Niskin bottles have been analysed by Winkler titration with an accuracy of 2.5 µmol/kg. In addition, samples for the analyses of CFC-12 and SF6 have been analysed on board by a capillary-chromatographic system with electron capture detector. This device is an advancement from the one described in: Bulsiewicz, K., H. Rose, O. Klatt, A. Putzka, and W. Roether (1998), A capillary -column chromatographic system for efficient chlorofluorocarbon measurement in ocean waters, J. Geophys, Res., 103, 15959-15970. CFC-12 and SF6 values are reported on the SIO-98 scale. Accuracy is 2.5% for SF6 and 2.0% for CFC-12, detection limt 0.01 fmol/kg for SF6 and 0.002 pmol/kg for CFC-12. The samples for the noble gas measurements were stored in copper tubes. The gas from the tubes was extracted with a ultra high vacuum extraction system and then analysed with respect to helium and neon at the mass spectrometer facility at the University of Bremen (department of oceanography). Analytical precision based on duplicate samples is 0.3% for helium and 0.4% for neon. The Bremen mass spectrometer facility has been described in detail in: Sültenfuß, J., M. Rhein, and W. Roether (2009), The Bremen Mass Spectrometric Facility for the measurement of helium isotopes, neon, and tritium in water. Isotopes in Environmental and Health Studies, 45(2), 1-13, doi:10.1080/10256010902871929.