The microbial methane cycle in subsurface sediments. Final project report, July 1, 1993--August 31, 1997
- Texas A and M Univ., College Station, TX (United States)
- Univ. of Oklahoma, Norman, OK (United States). Dept. of Botany and Microbiology
The objectives of this study were to determine the factors controlling microbial activity and survival in the subsurface and, specifically, to determine whether microbial communities in aquitards and in aquifer microenvironments provide electron donors and/or acceptors that enhance microbial survival in aquifers. Although the original objectives were to focus on methane cycling, the authors pursued an opportunity to study sulfur cycling in aquifer systems, a process of much greater importance in microbial activity and survival, and in the mobility of metals in the subsurface. Furthermore, sulfur cycling is pertinent to the Subsurface Science Program`s study at Cerro Negro, New Mexico. The study combined field and laboratory approaches and microbiological, molecular, geochemical, and hydrogeological techniques. During drilling operations, sediments were collected aseptically and assayed for a variety of microorganisms and metabolic capabilities including total counts, viable aerobic heterotrophs, total anaerobic heterotrophs, sulfate reducing bacteria (SRB) and sulfate reduction activity (in situ and in slurries), methanogens, methanotrophs, and Fe- and S-oxidizers, among others. Geochemical analyses of sediments included organic carbon content and {sup 13}C/{sup 12}C ratio, sulfur chemistry (reduced sulfur, sulfate), {sup 34}S/{sup 32}S, {sup 13}C/{sup 12}C, {sup 14}C, tritium, etc. The authors drilled eight boreholes in the Eocene Yegua formation at four localities on the Texas A&M University campus using a hollow-stem auger drilling rig. The drilling pattern forms a T, with three well clusters along the dip direction and two along strike. Four boreholes were sampled for sediments and screened at the deepest sand interval encountered, and four boreholes were drilled to install wells in shallower sands. Boreholes range in depth from 8 to 31 m, with screened intervals ranging from 6 to 31 m. Below are the results of these field studies.
- Research Organization:
- Texas A and M Univ., College Station, TX (United States)
- Sponsoring Organization:
- USDOE Office of Energy Research, Washington, DC (United States)
- DOE Contract Number:
- FG03-93ER61636
- OSTI ID:
- 639785
- Report Number(s):
- DOE/ER/61636-T1; ON: DE98006135; TRN: AHC29816%%93
- Resource Relation:
- Other Information: PBD: [1997]
- Country of Publication:
- United States
- Language:
- English
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