Trace Metals Amundsen Sea Araon ANA08B and Weddell Sea PS117 Version 26

Amundsen ANA08B: Samples were collected onboard the South Korean icebreaker RV Araon during the ANA08B research expedition to the Amundsen Sea in the austral summer of 2017/2018. The sampling period spanned from the 24th of January to the 2nd of February 2018. A total of 10 full depth stations were investigated with a maximum of 12 sampling depths. The transect followed the in- and outflow of CDW in the ASP through a trough near the Dotson ice shelf. The ASP was surrounded by sea ice at the start of the sampling campaign, whereas the polynya had started to open to the open ocean on the northwest side by the end of sampling. Along this transect, station 53 was located off the shelf and outside the polynya in the marginal sea ice zone, station 52 was located near the outermost edge of the polynya at the shelf break, stations 42 and 36 were located at the Dotson Ice Shelf front on the in -and outflow side respectively, and the remaining stations were located in the central open water body of the ASP. Water was collected with the ‘Titan’ ultraclean CTD sampling system for trace metals mounted with pristine large volume samplers. To prevent light shock of phytoplankton, the original PVDF samplers were replaced by a light-proof version of the Pristine samplers and were made from polypropylene. The salinity (conductivity), temperature, fluorescence, depth (pressure) and oxygen were measured with a CTD (Seabird SBE 911+) mounted on the trace metal clean sampling system of NIOZ. The sampling system was deployed on a 11 mm Dyneema cable without internal conductive wires and therefore an SBE 17 plus V2 Searam in a titanium housing provided power, saved the CTD data and closed the sampling bottles at pre-programmed depths. After deployment, the complete CTD sampling system was placed in a cleanroom environment inside a modified high cube shipping container and subsamples were collected.

Weddell Sea PS117: Samples were collected on board the German icebreaker RV Polarstern during the PS117 research expedition to the Weddell Sea in the austral summer of 2018/2019. The sampling period spanned from the 26th of January to the 1st of February 2019. A total of 23 (semi)full depth stations were taken with a maximum of 20 sampling depths. Samples for trace metals were collected along the prime meridian (0° W) transect in December/January 2018-2019 at 8 stations. Northernmost station 22 is located at 59°S and southernmost station 30 at 69.37° S. Additionally, 4 stations were samples near the ice sheet and in the Weddell Basin that were not along a transect. Due to the malfunctioning sampling system, deepest depths were not sampled correctly and can therefore not be used in the analysis. Along the Weddell Sea transect a total of 11 trace metal stations, of which 6 full depth, were sampled in January/February 2019. The transect starts in the Weddell Sea basin at station 61 (45.8°W) and followed the continental slope towards the West-Antarctic peninsula where the shelf station 95 was closest to the continent (54.5° W). Water was collected with the ‘Titan’ ultraclean CTD sampling system for trace metals mounted with pristine large volume samplers. To prevent light shock of phytoplankton, the original PVDF samplers were replaced by a light-proof version of the Pristine samplers and were made from polypropylene. The salinity (conductivity), temperature, fluorescence, depth (pressure) and oxygen were measured with a CTD (Seabird SBE 911+) mounted on the trace metal clean sampling system of NIOZ. The sampling system was deployed on a 11 mm Dyneema cable without internal conductive wires and therefore an SBE 17 plus V2 Searam in a titanium housing provided power, saved the CTD data and closed the sampling bottles at pre-programmed depths. After deployment, the complete CTD sampling system was placed in a cleanroom environment inside a modified high cube shipping container and subsamples were collected.