10 November - 16 November 2008

At the beginning of the week, it was still overcast and the sea remained calm. Monday, the 10th of November was used for the last testing of the Posidonia system and the Scanfish. The Scanfish is an oceanographic device, which can be towed behind the boat and remotely controlled to go up and down the water column to 400 m depth. It can measure parameters such as temperature, salinity, chlorophyll, turbidity etc.. For the testing of the depth measuring device (sonar) of the Scanfish, we went over a big seamount, which rises from the seafloor at 4000 m depth to only 100 m below the surface. The Scanfish is needed for intensive work during the third leg of this Antarctic campaign.

On the 11th of November, a farewell barbeque night was prepared on deck to say good-bye to the scientific members, who left us and debarked in Las Palmas, Gran Canaria. It was a memorable night with nice weather and warm temperatures. We are certain that people are envious at home. We approached Gran Canaria on the next morning, and the lights of Las Palmas welcomed us. We arrived at 7:00 a.m., and the Polarstern remained outside the harbour three sea miles offshore. An hour later a small boat arrived to pick up the 12 scientists, who left us. The small boat was rocking and rolling compared to the sturdy Polarstern, which set the scene for a sporty debarking, and people had to wait for the right condition to jump off the Polarstern onto the other boat. Shortly after, we were back at sea heading south.

A group of scientists from several nations is engaged in the chemical characterisation and composition of dissolved organic matter in the ocean. This material comprises one of the largest active organic pools on our planet, comparable to the amount of organic carbon stored in all land plants or in the atmospheric CO2. Although the amount of dissolved organic matter in the ocean is enormous the chemical nature of this extremely complex material is hardly identified. Our study addresses the question how fresh algal-derived material is altered by sunlight and bacterial degradation in different climatic zones, which Polarstern passes on her way from Bremerhaven to Cape Town. For this, large amounts of water from the surface and different water depths are enriched through different sorbents.

A special way to enrich substances happens at the sea surface. There, it foams and bubbles like in a glass of champagne. One can see it best when Polarstern passes through the waves. Trapped bubbles in seawater drag surface-active organic compounds, like an elevator, along their way through the liquid bulk, to reach the sea surface and finally burst and eject droplets into the atmosphere with their organic charge. The same happens with the water samples in the lab. In a special beaker, seawater bubbles and the droplets are produced and collected. In the laboratories at home all samples, collected with the various methods, will be analyzed with sophisticated technologies. The group hopes that their results will contribute to a better understanding of the origin and the modification of marine dissolved organic matter and by that contribute to a better understanding of its role in global change.

A rhythm of daily shallow CTD casts to 200 m depths and deep CTD casts to the sea floor every 4 days has been established during this week. After it had been a little bit more windy with wind forces up to 7 und overcast conditions, the sun returned and the wind dropped. Therefore, daily light measurements are possible again from the rubber boat.

Wind and current are pushing us direction south. The first flying fish were sighted and even one flew on deck. The air and temperature are tropical now between 26° and 27° C.

Warm greetings to everybody at home,

Gerhard Kattner