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:
During the first month of the project the students were trained on the various laboratory and sampling techniques.
The field remediation sites were set up and treated in mid-June 2001 and tilled in late June 2001. Samples were taken before remediation and one month after the first tilling but not at the end of the second month of treatment due to lack of rain. Not much has changed yet, which is not surprising for only one month of a field demonstration. The nutrient levels are higher in the fertilized plots than they were previously. Nitrate nitrogen levels dropped in plots where fertilizer was not added, and ammonia nitrogen levels have generally increased. The hydraulic conductivity is generally higher in the plots with added hay.
The microcosms were built and started at the end of July 2001. Initial samples, before treatment, and one-month samples have been collected and analyzed. Nutrient levels are higher where we added fertilizer. The hydraulic conductivity is generally higher in the microcosms with added hay. Almost all brine component concentrations have increased; we believe this may be due to the salt moving with water to the top of the soil and accumulating at the top of the microcosms when the water evaporates.
Future Activities:
The field sites will be sampled and tilled at the end of September. The microcosms will continue to be sampled and tilled on a monthly basis. A poster presentation and an oral presentation on the results to date will be made at the 8th Annual International Petroleum Environmental Conference in November 2001.
Supplemental Keywords: produced fluids, brine, organic matter, permeability, hydraulic conductivity, cation exchange capacity, aggregate stability, bioremediation, microcosm, field study