Because of the difficult ice conditions our progress was very slow. South of 89° 30’N our average speed was only 1 knot, so that a considerable delay was building up with respect to our station schedule. Since we intended to turn west at 88° 15’ N anyway, we decided to cut the corner and turn earlier. However, we were only partly successful since large ice floes were in our way and the ice cover was 100%. The thick layer of snow also made it difficult to distinguish the edges of the floes. Therefore we could conduct a combined water and ice station only at September 11 instead of September 10. After having found a suitable ice floe its thickness was determined by electromagnetic measurements and in parallel ice cores were taken for the determination of a number of biogeochemical parameters.

In addition, another French iAOOS buoy was deployed together with an English ice thickness buoy and a webcam. During the ice station the sun was shining but nevertheless it was rather cold with -11°C. Parallel to the ice work we conducted again casts with the Large Rosette and the Ultra-Clean-Rosette for the GEOTRACES program. In the following, the Dutch chemist Loes Gerringa and the Spanish chemist Nuria Casacuberta describe the task and the sampling procedure of GEOTRACES:

GEOTRACES (www.geotraces.org) is an international program that aims to determine global ocean distributions of selected trace elements and isotopes, including their concentration, chemical speciation and physical form, and to evaluate the sources, sinks and internal cycling of these species. This knowledge is needed to characterize more completely the physical, chemical and biological processes regulating their distributions. In this way the response of these cycles to global climate change can be predicted, and their impact on the carbon cycle and climate understood.  Moreover, the possible perturbation of the biogeochemical cycles by anthropogenic inputs of Hg, Pb, Cd, and Zn is still largely unknown.

It is a good custom that within the international GEOTRACES group we take samples for each other(‘s institutes), saving time and money. This means that we are not only sampling for the scientists on board but also for colleagues all over the world. On board we sample sea water with a special rosette, the so called ultra-clean (UC) rosette. With this rosette it is possible to sample water in which isotopes and trace elements like iron can be measured. This cannot be done with the conventional rosette since cable and rosette are made of steel, giving off trace elements to the water samples. In order to prevent this unwanted contamination the ultra-clean rosette is made of titanium, the cable on which the rosette is lowered is made of a non-metallic material (Dyneema) and the 24 bottles of 27 L each are made of clean plastic (polypropylene). As soon as this rosette is coming out of the water it is put on a special sledge (and NOT on the deck of Polarstern) which is rolled to a container. From the sledge the rosette is pushed into the container which has a clean air system. People sampling have to dress in dust-free coveralls, clean boots, gloves and caps. And then the tedious job of filling all the different bottles begins for our own team and for the colleagues at home who requested samples from this cruise. For popular stations this means that some rosette bottles, each representing a different depth, have 19 (!) bottles waiting in line to be filled, either unfiltered or filtered under nitrogen pressure. This rosette allows us to sample a normal station within 2 hours, and a special (called super …!) station within 3 hours. Without this rosette in its clean container sampling would have taken twice as much time. The team doing this job consists of Micha Rijkenberg, Lars-Eric Heimburger, Michael Staubwasser, Aridane Gonzalez and Hans Slagter.

After that we continued our section westward, alternating between throwing XCTDs and doing a station with the large rosette and the Ultra-Clean rosette. On September 12. we arrived at the next corner position for turning south west and at this position we conducted a combined ice /water sampling station. Besides using the usual instruments we sampled here also with the In-situ pumps and obtained sediment samples using the multi-corer. Unfortunately the ice work was hampered through bad visibility.

With best regards,

In the name of all participants, Ursula Schauer

The GEOTRACES description was written by Loes Gerringa and Nuria Casacuberta