Project GB3

K.U. Hinrichs and T. Ferdelman
A. Boetius, B. Brunner, M. Elvert, V. Heuer, Y.-S. Lin, B. Koch, M. Zabel

In the last decade, research of the marine subsurface biosphere has provided new insights into the taxonomic composition and sedimentary distribution of microbial populations and the metabolic rates that sustain these populations. On the other hand, important new questions have arisen and motivate our research strategy for Project GB3. With the proposed research, we aim to (i) develop a better understanding of a dominant group of subsurface microbes, i.e., benthic Archaea, (ii) test and apply new isotopic assays for constraining rates and importance of S-based respiration, (iii) constrain the geomicrobial relevance of novel reactions coupling the sedimentary C- and S-cycles, and (iv) examine how and what fraction of refractory organic carbon is being utilized by microbial activity. Our research will be based on a combination of laboratory-based experiments using subsurface sediments and field observations. Field samples from a range of subsurface depths are/will be available from recently completed or planned expeditions, including Guaymas basin, Manus basin, mid-Atlantic Ridge (North Pond), equatorial Pacific, and the continental margins off Namibia, Makran, and Oregon.