Study of ecological indicators in bioremediation and restoration of crude oil contaminated soil

The Nature Conservancy's (TNC) Tallgrass Prairie Preserve (TGP) in Osage County, OK, has more than 39,000 acres of grassland, about 2400 bison, and over 100 active oil wells. On January 6th, 1999, 70 barrels of dewatered crude oil from a pipeline rupture contaminated two areas of the prairie, J6 North- 930 m2 and J6 South- 440 m2 with initial total petroleum hydrocarbon (TPH) concentrations in J6 North- 33,500 mg/kg and J6 South- 4,800 mg/kg. In situ landfarming was used to remediate the contaminated areas. To compare treatments, J6 North and J6 South impacted areas were divided into fertilized and non-fertilized sections. Two types of controls, namely unimpacted, undisturbed native prairie control and unimpacted but disturbed by tilling control were used for comparison.; Another area of the prairie (Revegetation study site, 440 m2) was contaminated by crude oil in 1992 and remediated in 1996 using ex situ landfarming. In 2001, vegetation on the impacted area (excavated site) and the treatment area (landfarm site) were investigated by comparing to an adjacent unimpacted and undisturbed native prairie control.; This dissertation discusses results for TPH, ecological indicators such as viable microbial biomass and nematode community, nutrient dynamics, and DNA. Revegetation analysis such as species richness, species diversity, and aboveground plant biomass is also discussed.; By October 2003, the TPH concentration in J6 was reduced significantly to <500 mg/kg. In J6 North, a statistical difference was observed with faster TPH removal rate in the fertilized area compared to the non-fertilized area. However, in J6 South, there was no statistical difference in TPH reduction rates. The ecological indicators studied in J6 North clearly showed that the non-fertilized area lagged substantially behind the fertilized area in terms of the impacted soil ecosystem recovery. In contrast, J6 South fertilized and non-fertilized areas showed similar rates of recovery. Nematodes (total number and trophic diversity) proved to be a sensitive and economic ecological indicator for the soil ecosystem recovery.; Revegetation analysis on different site showed that the vegetation on the excavated and landfarm sites was still disturbed. There was growth of more exotic plant species compared to control.