During the Polarstern TransARC II cruise (PS94) expedition water samples were taken in the Arctic Ocean north of 71 °N, between 17 August and 14 October 2015. The cruise was part of the international GEOTRACES program. Samples for trace metal analysis were taken using 24 trace-metal clean polypropylene samplers of 24 L, each mounted on an all titanium frame with a SEABIRD 911 CTD system. In an ISO Class 6 clean room container the samples were immediately filtered over < 0.2 µm Sartobran 300 cartridges and acidified. The dissolved trace metals cadmium (Cd), cobalt (Co), copper (Cu), iron (Fe), manganese (Mn), nickel (Ni), zinc (Zn) were analysed at the Netherlands Institute for Sea Research with a Thermo Finnigan High Resolution Inductively Coupled Plasma Mass Spectrometer (HR-ICP-MS) element 2 after pre-concentration and matrix removal. This study provides a baseline to assess future change, and additionally identifies processes driving bio-essential trace metal distributions.

In a few cases (casts) CTD data is missing, this was due to malfunction of the Ultra clean ctd (UCC). Depths, salinity, temperature were obtained from the normal CTD, an extra check for correct depths was done by comparing nutrient data from other casts (three ctd systems were applied).Empty cells = nd