Microbial Dynamics in Oil-Impacted Prairie Soil

Abstract

A remote site in the Tallgrass Prairie Preserve (Osage County, OK) was contaminated with crude oil by a pipeline break in 1992. In 1996, the contaminated soil was bioremediated by blending with uncontaminated soil, prairie hay, buffalo manure, and commercial fertilizers, and spreading in a shallow layer over uncontaminated soil to create a landfarm. The landfarm was monitored for two years for aerobic and anaerobic bacteria, soil gases indicative of microbial activity, and for changes in the concentration of total petroleum hydrocarbons (TPH). Levels of hydrocarbon degraders and soil gas indicators of aerobic degradation were stimulated in the landfarm during the first warm season relative to uncontaminated prairie soil. However, these same indicators were less conclusive during the second warm season, indicating depletion of the more easily degradable hydrocarbons, although the landfarm still contained 6,800 mg/kg TPH on the average at the beginning of the second warm season. Methane formation and methanogen counts were clearly stimulated in the first warm season relative to uncontaminated prairie soil, indicating that methanogenesis plays an important role in the mineralization of hydrocarbons even in these shallow soils.

Effect of Environmental Factors on the Abundance of Culturable Nitrate Reducing/Denitrifying Bacteria from Contaminated and Uncontaminated Tallgrass Prairie Soil

“…Leaks from oil pipelines had contaminated the sites with crude oil (J6-F, J6-NF, LF) or with a mixture of brine and oil (G5, G7). The sites had been partially remediated as described previously (Sublette et al, 2005;Sublette et al, 2007a;Duncan et al, 1998;Duncan et al, 1999). Briefly, the contaminated sites were contaminated during 1996-2000 but still contained low levels of TPH and Na + and Cl -(Tables 1.a and 1.b) when sampled for the current study.…”

“…Sodium and chloride levels varied widely, with sodium ranging from 350-600 mg/ kg soil (Sublette et al, 2004). On the other hand, LF, containing soil contaminated by a spill of crude oil, was remediated in 1996 and 1997 by mixing the contaminated soil with the uncontaminated soil plus nitrogen-containing fertilizer (Duncan 1998(Duncan , 1999. During that time, TPH levels decreased to about a third of the original level and plants grew over most of the site, but they were primarily weedy, non-native, undesirable species.…”

“…Nitrate was measured in Oklahoma State University Laboratory (Stillwater, OK, USA). Metadata was collected from different studies that include TPH, Na + , Cl -, and NO 3 in contaminated-treated (G5, G7, LF, J6-F, and J6-NF) and prairie (G5P, G7P, LFP, and J6P) sites (Duncan et al, 1999;Sublette et al, 2005;Sublette et al, 2007a).…”

Reclamation of Hydrocarbon Contaminated Soils Using Soil Amendments and Native Plant Species

“…Petroleum hydrocarbon contaminated soils commonly have imbalanced nutrient ratios due to the large input of carbon from the fuel. Immobilization of available nutrients occurs when carbon to nutrient ratios increase, therefore inorganic fertilizers, such as ammonium sulphate, are applied to contaminated soils to supply readily available nutrients to the microbial populations [13,34,35]. Compost as an amendment was mixed with soil at 20% (dry soil mass, equivalent to 10% wet soil volume) in compost and compost-fertilizer treatments.…”

Multi-Species Ecotoxicity Assessment of Petroleum-Contaminated Soil

“…After mixing thoroughly by vortexing, the suspension was diluted and spread (three replicates) on the following types of media: Plate Count Agar with cyx ("PCA", Difco Co., Detroit, MI) for total aerobic heterotrophs; mineral salts (MS) agar with trace metals (Duncan et al, 1999), and 100 µg/mL cyx containing one of the following aromatic hydrocarbons: (1) toluene added as a liquid to filter paper placed on the bottom of a glass petri plate lid for toluene-degraders (TOL), (2) naphthalene added as crystals on the bottom of the plate lid for naphthalenedegraders (NAP), (3) MS agar containing 0.8% phenanthrene for phenanthrene degraders (PHE). All plates were incubated at room temperature.…”