In situ degradation of oil in a soil of the boreal region of the Northwest Territories.

Replicate field plots comprising a control; control plus oil; control plus oil and fertilizer (urea phosphate, 27:27:0); control plus oil and bacteria; and control plus oil, fertilizer, and bacteria were established at Norman Wells, N.W.T., Canada. Plots were monitored over a 3-year period for changes in microbial numbers and the chemical composition of recovered oil. Where fertilizer was applied, there was a rapid increase in bacterial numbers, but no increase in fungal propagules. This was followed by a rapid disappearance of n-alkanes, isoprenoids, and a continuous loss in weight of saturate compounds in recovered oil. Changes in the content of asphaltenes, aromatics, and nitrogen-, sulphur-, and oxygen-containing fractions also are discussed. The seeding of oil-soaked plots with oil-degrading bacteria did not have any effect on the composition of recovered oil. Fertilized plots showed a more rapid rate of vegetation with cotton grass and Labrador tea being the dominant species in revegetation.