DEGRADATION OF HYDROCARBON SLUDGES IN THE SOIL

Abstract

Hydrocarbon residues from crude oil storage tanks were incorporated into field plots of a Red River Clay soil. The oil content immediately after application was 1.45% based on the weight of air-dried soil. The plots were sampled after application and after 106, 476 and 833 days. Hydrocarbons were extracted from samples with tetrahydrofuran at room temperature and fractionated by a combination of solvent extraction and column chromatography into the following fractions: (1) saturates, (2) monoaromatics, (3) diaromatics, (4) polyaromatics and polar compounds and (5) high molecular weight material such as asphaltenes. Fractions (1) to (4) were examined by gas–liquid chromatography. The results showed that 50.4% of the total applied residues were degraded within 833 days. The individual fractions were degraded to varying extents: (1) 54.6%, (2) 50.0%, (3) 57.1%, (4) 44.4% and (5) 11.1%. The alkanes in fraction (1) degraded to low levels during the first 106 day s.