Pore-water advection and organic matter mineralization in North Sea shelf sands Dissertation zur Erlangung des Doktorgrades der Naturwissenschaften Dem Fachbereich Biologie / Chemie der Universität Bremen vorgelegt von Felix Janssen Bremen im Februar 20042 Die vorliegende Arbeit wurde in der Zeit von Juli 1999 bis Februar 2004 am Max-Planck-Institut für marine Mikrobiologie in Bremen angefertigt. Gutachter Prof. Dr. Bo Barker Jørgensen (Erstgutachter) Prof. Dr. Venugopalan Ittekkot (Zweitgutachter) Prüfer Prof. Dr. Dieter Wolf-Gladrow Dr. Ursula Witte Weitere Mitglieder des Prüfungsausschusses Priv. Doz. Dr. Matthias Zabel Stud. rer. nat. Patricia Wecker Datum des Promotionskolloquiums: 2. April 2004 3 Acknowledgements I would like to thank Prof. Bo Barker Jørgensen for accepting me as a PhD student and for supporting this work. I am most grateful to my mentor Dr. Ursula Witte, who greatly supported me in numerous ways during the entire PhD project. Often it was her ability to separate important from irrelevant things that helped a lot whenever things got complicated, e.g. during cruise preparation, last minute technical developments, and manuscript writing… Dr. Markus Hüttel is thanked very much for a lot of help and for sharing his great experience in the field of sandy sediments from the initial thesis planning all the way to critical manuscript reading. I’d further like to thank Prof. B. B. Jørgensen and Prof.