Description: Artificial radionuclides have been introduced to the oceans from nuclear weapons tests (1950’s-1960’s), nuclear accidents (e.g. Chernobyl, 1986) and nuclear reprocessing plants (Sellafield, and La Hague, from 1960s until today) and since then they are used as transient tracers for ocean circulation. Among these radionuclides, 129I and 236U have become of special interest in the last decade and the combination of 129I/236U to 236U/238U atom ratios has been suggested as a tool to determine transit times in the Arctic Ocean [1] and to constrain the source of the anthropogenic contamination [2]. The performance of this new dual tracer has now been tested as data from samples collected during several cruises performed in the North Atlantic and Arctic oceans. Here we present the results of a number of expeditions to the Arctic Ocean (2011, 2012 and 2015) and the North Atlantic Ocean (2010, 2014). Atlantic waters entering the Arctic Ocean are tagged with high 129I/236U ratios (〉100) and 236U/238U ratios (〉1000 x10-12), originating from more recent (〈15 years) releases from reprocessing plants. Deep and bottom waters in the Arctic Ocean have much lower 129I/236U and 236U/238U ratios (supported by low 14C concentrations), representing the isolation of these waters from anthropogenic signals. New data from Barents Sea Branch Waters indicate the presence of a stronger signal from waters tagged by La Hague while Fram Strait Branch Waters, show a mixture of both Sellafield and La Hague endmembers. In order to better disentangle the sources and fate of 129I and 236U to the North Atlantic and Arctic oceans, results from a global ocean model will be presented and discussed in the context of the experimental data. [1] Christl et al. (2015) J. Geophys. Res. Oceans, 120. [2] Casacuberta et al. (2016) Earth Planet. Sc. Lett. 440.

Description: Ice drift recorded by ice buoys show a relatively direct pathway of ice from the North Pole to Fram Strait. An ice tethered buoy deployed in 2015 during GEOTRACES section GN04 at 89°N was recovered in August 2016 at 76°43N in Fram Strait during GEOTRACES section GN05. Does the surface water follow a similar pathway? Tracer data collected during these two expeditions are used to investigate to what extent the water in the East Greenland Current (EGC) can be considered a downstream extension of the Transpolar Drift (TPD) at the North Pole. The reduction of 228Ra activities and 129I/236U ratios in the EGC compared to the TPD can be explained either by a much longer (order 3-4 years) travel time than suggested by the ice drift, or by admixture of surface waters from other, presumably Pacific sources. The pathways followed by surface water in a coupled sea-ice-ocean model suggest that the transit of surface water is indeed much more erratic and time consuming than the transit of ice. We will discuss whether N/P ratios or Nd isotopes give evidence for a change in the contribution of Pacific waters.

Description: Water column raw data using the ship's own Kongsberg EM 710 multibeam echosounder was not continuously recorded during RV METEOR cruise M122. Data was recorded on 6 days between 2015-12-31 and 2016-01-15. The data are archived at the Federal Maritime and Hydrographic Agency of Germany (Bundesamt für Seeschifffahrt und Hydrographie, BSH) and provided to PANGAEA database for data curation and publication. Ancillary sound velocity profiles (SVP) files from the cruise are archived at the BSH and added to the corresponding multibeam raw dataset https://doi.org/10.1594/PANGAEA.945015 This publication is conducted within the efforts of the German Marine Research Alliance in the core area 'Data management and Digitalization' (Deutsche Allianz Meeresforschung, DAM).

Description: Multibeam bathymetry raw data using the ship's own Kongsberg EM 122 multibeam echosounder was almost continuously recorded during RV METEOR cruise M122. Data was recorded on 33 days between 2015-12-30 and 2016-01-31. This dataset contains a survey towards the coast of Namibia & Angola. The approximate average depth of the entire dataset is around 700m. The data are archived at the Federal Maritime and Hydrographic Agency of Germany (Bundesamt für Seeschifffahrt und Hydrographie, BSH) and provided to PANGAEA database for data curation and publication. Ancillary sound velocity profiles (SVP) files from the cruise are archived at the BSH, thus SVP files are added to this dataset. Also data analysis of the multibeam raw data revealed that SVP has been changed during the survey. This publication is conducted within the efforts of the German Marine Research Alliance in the core area 'Data management and Digitalization' (Deutsche Allianz Meeresforschung, DAM). Data are unprocessed and therefore contains incorrect depth measurements (artifacts) without further processing. Note that refraction errors can be expected due to the lack of proper SVP. Overall, it appears that the data quality is rather good since the gridded hillshade data showed relatively few obstacles. Data acquisition has been monitored at all times during surveying. Data can be processed e.g. with the open source software package MB-System (Caress, D. W., and D. N. Chayes, MB-System: Mapping the Seafloor, http://www.mbari.org/products/research-software/mb-system/, 2022).

Description: Water column raw data using the ship's own Kongsberg EM 122 multibeam echosounder was not continuously recorded during RV METEOR cruise M122. Data was recorded on 10 days between 2015-12-31 and 2016-01-27. The data are archived at the Federal Maritime and Hydrographic Agency of Germany (Bundesamt für Seeschifffahrt und Hydrographie, BSH) and provided to PANGAEA database for data curation and publication. Ancillary sound velocity profiles (SVP) files from the cruise are archived at the BSH and added to the corresponding multibeam raw dataset https://doi.org/10.1594/PANGAEA.945013 This publication is conducted within the efforts of the German Marine Research Alliance in the core area 'Data management and Digitalization' (Deutsche Allianz Meeresforschung, DAM).

Description: Multibeam bathymetry raw data using the ship's own Kongsberg EM 710 multibeam echosounder was almost continuously recorded during RV METEOR cruise M122. Data was recorded on 25 days between 2015-12-30 and 2016-01-23. This dataset contains a survey towards the coast of Namibia & Angola. The approximate average depth of the entire dataset is around 400m. The data are archived at the Federal Maritime and Hydrographic Agency of Germany (Bundesamt fÃür Seeschifffahrt und Hydrographie, BSH) and provided to PANGAEA database for data curation and publication. Ancillary sound velocity profiles (SVP) files from the cruise are archived at the BSH, thus SVP files are added to this dataset. Also data analysis of the multibeam raw data revealed that SVP has been changed during the survey. This publication is conducted within the efforts of the German Marine Research Alliance in the core area 'Data management and Digitalization' (Deutsche Allianz Meeresforschung, DAM) Data are unprocessed and therefore contains incorrect depth measurements (artifacts) without further processing. Note that refraction errors can be expected due to the lack of proper SVP. Overall, it appears that the data quality is rather good since the gridded hillshade data showed relatively few obstacles. Data acquisition has been monitored at all times during surveying. Data can be processed e.g. with the open source software package MB-System (Caress, D. W., and D. N. Chayes, MB-System: Mapping the Seafloor, http://www.mbari.org/products/research-software/mb-system/, 2022).