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Preparation of Authigenic Pyrite from Methane-bearing Sediments for In Situ Sulfur Isotope Analysis Using SIMS
Published on: August 31, 2017
Spatial variability of sulfate reduction in a shallow aquifer
Chris L Musslewhite1, Don Swift, Johnnie Gilpen
1The University of Oklahoma, Department of Botany and Microbiology, 770 Van Vleet Oval, Norman, OK 73071, USA.
Environmental Microbiology
|October 10, 2007
Summary
Sulfate-reducing bacteria (SRB) activity in aquifers is mainly controlled by sediment porosity and pore size, not depth or bacterial numbers. Smaller pores limit SRB metabolism and growth, impacting their distribution.
Area of Science:
- Environmental microbiology
- Geomicrobiology
- Aquifer science
Background:
- Sulfate-reducing bacteria (SRB) play a crucial role in biogeochemical cycles within aquifers.
- Understanding the factors controlling SRB distribution and activity is vital for aquifer management and understanding subsurface processes.
Purpose of the Study:
- To investigate the distribution and metabolic activity of SRB in a shallow, suboxic aquifer.
- To identify the key environmental factors influencing SRB metabolic rates at a centimeter scale.
Main Methods:
- Utilized a radioimaging technique for visualizing and quantifying SRB activity in sediments.
- Analyzed correlations between SRB activity and various sediment properties including depth, bacterial numbers, sediment type, grain size, permeability, hydraulic conductivity, and porosity.
- Employed controlled column experiments with varying pore diameters to assess the impact of pore size on SRB metabolism.
Main Results:
- SRB metabolic activity exhibited heterogeneous distribution, with limited high-activity zones.
- SRB activity showed a significant positive correlation with sediment porosity (r = 0.48).
- Experimental columns demonstrated that smaller pore diameters significantly reduced SRB metabolic rates, while larger pores enhanced them.
Conclusions:
- Sediment porosity and pore size are identified as the primary factors controlling SRB activity in the studied aquifer.
- Small pore sizes appear to restrict SRB growth and nutrient access, thereby limiting their metabolic activity.
- Findings highlight the importance of micro-scale physical properties in regulating microbial processes in subsurface environments.
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