2011 Sediment Biogeochemistry Meeting

Theme: Biogeochemistry in marine sediments

a) Drill cores
b) Biogeochemistry in marine sediments

Date: 2011

Host: University of Bremen, Germany (UB)

Organizers: Kai-Uwe Hinrichs - chair, Wolfgang Bach (both at UB), Bo Barker Jørgensen (Max-Planck Institute & University of Aarhus, Denmark)

Scientific Conference. Biogeochemistry of the deep sedimentary biosphere will be the scientific theme of the meeting in Bremen. Marine sediments cover 70% of the Earth's surface and contain perhaps the largest reservoir of microbial biomass on Earth (Lipp et al.; Whitman et al. 1998). The ecology and physiology of the microorganisms in the vast realm of subsurface sediments remain enigmatic, despite their high genetic diversity and physiological potential (Jørgensen and Boetius 2007). Slow degradation of organic matter supports microorganisms down to depths of at least 1600 meters below the seafloor in over 100 Million year old sediments and at temperatures up to 100°C (Roussel et al. 2008). Even in extremely low-energy environments, radiolytic cleavage of water may support appreciable numbers of microbial cells (about 10^5 cells/cm³); (Blair et al. 2007). Availability of energy from organic carbon degradation and cell numbers both decrease with increasing depth in the sediments, but the specific relationships with the sediment's physical properties and temperature are poorly constrained. Largely unconstrained are also the consequences of changing palaeoceanographic conditions that result in vertically varying concentrations of substrates nutrients. The science conference part of the Bremen meeting will provide a forum for presenting and discussing the most recent results in marine sediment biogeochemistry and identifying the most pressing challenges that lie ahead.
Education Workshop. The workshop in Bremen will focus on recent developments in biogeochemical approaches employed to assess the diversity and activity of the deep sedimentary biosphere. A visit to the IODP core repository on campus is also planned to show first-hand the rock samples currently available for study. In the aftermath of the first dedicated sedimentary deep biosphere drilling expedition of the ODP Leg 201 six years ago, large strides have been made towards detecting microbial activity in deep drill cores and determining the incredibly slow rates of carbon turn-over (e.g., D'Hondt et al. 2004; Biddle et al. 2006). New directions in sedimentary biogeochemistry will be presented and discussed. These include quantitative applications of the most recent molecular probes and isotopic analysis of metabolites microbial cell constituents. Also discussed will be geochemical contamination tests of drill core samples. In analogy, to the ECORD summer school on the Deep Biosphere in September 2008, we are planning to provide a "virtual ship" experience in the facilities of the IODP core repository in Bremen. Workshop participants will learn details of shipboard core recovery, sampling, and other techniques pertinent to subseafloor biosphere expeditions.