Quantitative Chemical Mass Transfer in Coastal Sediments during Early Diagenesis: Effects of Biological Transport, Mineralogy, and Fabric: Phase 3.

摘要

LONG-TERM GOALS. Program goals were to provide a better quantitative and mechanistic understanding of chemical processes that occur in fine-grained coastal and continental margin sediments. Our long-term goal is to understand how the chemical and textural characteristics of sediments comprised of different clay mineral suites might exert a selective pressure on the development of natural consortia of bacteria. OBJECTIVES. The overall goal of this project is to evaluate the mechanism controlling the selection of different physiological groups of bacteria by defined clay minerals typically found in sea floor mineral assemblages, as well as quartz, the most common sedimentary mineral. Specifically our objectives were to: (1) create reproducible anaerobic microbial consortia associated with different monomineralogic substrates and to assess how stable they are over time; (2) determine changes in the textural and physical properties of mono-minerals as a result of microbial activity; (3) evaluate whether controlled mixtures of minerals and microbial communities can be used to create geomicrobiological assemblages with predictable ecological and physiological properties. APPROACH. We hypothesize that defined minerals can select specific physiological groups of microorganisms due to differences in their structure and composition, and thereby produce mineral/microbial assemblages with predictable properties. We are investigating two major groups of anaerobes, sulfate and metal (iron)- reducing bacteria, because they are abundant in marine environments, well adapted to environments with large gradients or changing in physical-chemical environmental conditions, and have a great capacity to oxidize and reduce a large variety of electron donors and acceptors. .