Comparison between Geochemical and Biological Estimates of Subsurface Microbial Activities

• Published in: Microbial ecology Vol. 28; no. 3; pp. 335 - 349
• Main Authors: T. J. Phelps, Murphy, E. M., S. M. Pfiffner, White, D. C.
• Format: Journal Article
• Language: English
• Published: New York, NY Springer-Verlag New York Inc 01-01-1994; Springer
• Subjects: Acetates; Animal, plant and microbial ecology; Aquifers; Biological and medical sciences; Carbon dioxide; Fundamental and applied biological sciences. Psychology; Geochemistry; Groundwater; Metabolism; Microbial activity; Microbial ecology; Oxygen; Sediments; Sulfates; Various environments (extraatmospheric space, air, water); United States; North America; South Carolina; America; USA; Microbial activity; Organic carbon; Aquatic environment; Ground water table; Radiolabelling; Investigation method; Biogeochemical cycle; Metabolism; Sediments; Microbial biomass; Ground water; Coastal plain
• ISSN: 0095-3628; 1432-184X
• DOI: 10.1007/BF00662027

Geochemical and biological estimates of in situ microbial activities were compared from the aerobic and microaerophilic sediments of the Atlantic Coastal Plain. Radioisotope time-course experiments suggested oxidation rates greater than millimolar quantities per year for acetate and glucose. Geochemical analyses assessing oxygen consumption, soluble organic carbon utilization, sulfate reduction, and carbon dioxide production suggested organic oxidation rates of nano- to micromolar quantities per year. Radiotracer timecourse experiments appeared to overestimate rates of organic carbon oxidation, sulfate reduction, and biomass production by a factor of$10^{3}-10^{6}$greater than estimates calculated from groundwater analyses. Based on the geochemical evidence, in situ microbial metabolism was estimated to be in the nano- to micromolar range per year, and the average doubling time for the microbial community was estimated to be centuries.