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Objective(s) of the Research Project:
The overall objective of this project is to study the possible positive effect of organic matter in the remediation of brine-impacted soil. The efficacy of this treatment will be quantified in a field study conducted in the Tallgrass Prairie Preserve in Osage Co., Oklahoma and in a companion microcosm study at the University of Tulsa. The microcosm study will attempt to identify the mechanism or mechanisms of action of the organic matter, which include: 1) a strictly physical effect on the texture of the soil; 2) an enhancement of the cation exchange capacity of the soil; 3) an enhancement of the water-stable aggregates formed from organic matter and soil mineral particles. Given that the all three of these mechanisms are affected by microbial action on the hay, the microbial populations will be determined both qualitatively and quantitatively, and then correlated with the results of the field and laboratory studies.
Progress Summary/Accomplishments:
Both microcosms and field sites are running. The field sites were sampled and tilled at the beginning of January. The microcosms were sampled at the beginning of January and February.
We cannot draw any firm conclusions from our results so far. The inhomogeneity of soil samples and small number of samples give us unclear or uncertain trends, so the results given next are tentative. The hay may have increased the cation exchange capacity in the field plots over time. The hydraulic conductivities of the microcosms with hay are higher than those without hay. Hay seems to have stimulated both prokaryote and eukaryote growth in the microcosms, and the eukaryote growth seems to be primarily fungi. This stimulated growth is what we hope will improve soil permeability and thereby salt removal via the second and third mechanisms.
A pre-proposal for a continuation of this project has been submitted to the Industrial Advisory Board. The continuation will support an extension of the field study.
Publications/Presentations:
Kim Carter, Brooke Mason, Laura Ford, Thomas Harris, and Kerry Sublette, The Use of Hay in the Remediation of Oilfield Brine-impacted Soil, 8th Annual International Petroleum Environmental Conference, November 2001.
Future Activities:
The field sites will be sampled and tilled at the beginning of April. This will be the last field sampling for the first year of the project, and these samples will include core samples to check the vertical distribution of the salt components.
The microcosms will continue to be sampled and tilled on a monthly basis. The microcosm samples taken in May will include samples for denaturing gradient gel electrophoresis and subsequent sequencing of some isolated bands for identification of prominent microbes.
Supplemental Keywords: produced fluids, brine, organic matter, permeability, hydraulic conductivity, cation exchange capacity, aggregate stability, bioremediation, microcosm, field study