POLARSTERN - Log 6 - Fern vom Uni-Alltag (Teil 4)
Summerschool der besonderen Art
Bericht des amerikanischen Ozeanographiestudenten Robert Letscher
This is Robert Letscher and I am a graduate student studying chemical oceanography at the Rosenstiel School of Marine and Atmospheric Science at the University of Miami in Florida, USA. On August 12, 2008, I boarded the German icebreaker, the Polarstern, and embarked on a journey around the globe in less than 80 days. We were headed for the Arctic Ocean and scientific research was the goal of our expedition. Some were searching for keys to reconstructing the Arctic basin’s history by looking in the sediments of the deep, some were intent on finding the creatures living within the water and ice, and some came to investigate the nature of the water itself. It is this latter pursuit that has brought me to the top of the world in my scientific endeavors.
POLARSTERN: Rast an der Eischolle. Bild: AWI Bremerhaven
Where has all the carbon gone?
My research program aboard the Polarstern this summer involved the study of the carbon system of the Arctic Ocean. The cycling of the element carbon through the earth system is important in sustaining life and is involved in a number of processes that regulate climate. The amount of carbon dioxide in the atmosphere is important in regulating temperature through the so-called greenhouse effect. This carbon dioxide from the atmosphere also finds its way into the oceans where it is fixed into organic material by the process of photosynthesis. It is my interest in the fate of this organic material found in the world oceans that has brought me to the Arctic to study the carbon system here, i.e., How does organic material enter the Arctic Ocean and where does it go/what happens to it once it gets there?
CTD-Rosette zur Gewinnung von Wasserproben aus den Tiefen des Antarktischen Ozeans. Bild: AWI Bremerhaven
Following the water molecules
To accomplish this goal, I was sent by researchers at my home university to collect a number of water samples from the surface waters of the Arctic Ocean. To quantify the amount of organic material in the waters, I collected samples for the analysis of dissolved organic carbon (DOC). Necessary to the understanding of the carbon system in the Arctic and to aid in answering the questions I posed earlier, some knowledge of the circulation of the waters via currents and exchange of waters between the continental shelf and ocean basin regions is needed. To accomplish this a number of samples were collected for analysis of isotopic tracers found in the water. Radium is a radioactive element found in trace quantities in sediments. Waters overlying the continental shelves are in close contact with the sediments and pick up some of this radium. By measuring the concentration of the different radioactive isotopes of radium in the water, we can begin to elucidate the pathways of waters as they circulate from the shelf to the ocean basins. These tracers along with others such as the stable isotopic signature of the oxygen in the water molecules themselves can be applied to the DOC data to further our understanding of the carbon system in the Arctic Ocean.
All in all, the cruise has been a success and I believe all aboard are content with the samples, data, and knowledge obtained on this voyage. This trip has been especially rewarding for me as a foreign student, joining the Germans and other Europeans in life at sea for almost ten weeks. Everyone has been most friendly and helpful and I have gained a better understanding of German culture. There is much to learn from each other and I hope that scientific partnerships between institutions and countries continues in the years to come so that others can enjoy the experience I was afforded on this occasion.
Das ScienceLog POLARSTERN ist eine Kooperation des Alfred-Wegener-Instituts für Polar-und Meeresforschung in der Helmholtz-Gemeinschaft mit planeterde.de.
