LONG-TERM COMPOSITION CHANGES OF OIL
RESIDUES IN PATAGONIAN SOILS
N. S. Nudelman*
Department of Organic Chemistry
Facultad de Ciencias Exactas y Naturales
Universidad de Buenos Aires
Pab. 2 Ciudad Universitaria
1428 Buenos Aires
Argentina
Voice: 541145763355
Fax: 541145763346
E-mail: nudelman@qo.fcen.uba.ar
S. M. Ríos
Facultad de Ciencias Naturales
Universidad Nacional de la Patagonia San Juan Bosco
Argentina
This paper examines the interdependence between the oil residue desorption fate and the shifts in the oil residual composition due to natural environmental processes. Experimental data of several parameters (nC17/pristane, nC18/phytane, content of the aliphatic, aromatic, polar and asphaltene fractions, etc.) determined for different regional field samples (spills), show that the changes in the chemical composition of the residues correlate better with exposure time in hydrophobic environments than with other variables such as the initial spill crude oil source or the soil composition. The results show an increase of the polar fraction during the first years and a continuous decrease in the nC17/pristane, nC18/phytane ratios when the environmental exposure time increases. An increase of the distribution coefficients (Kd) with age can be also observed. This could be attributed, not only to the loss of the more soluble components, but it also suggests that sequestration may be an important process. The influence of assistant degradation was also evaluated.
Key words: Oil spill, Polluted Patagonian soils, Distribution coefficients, Natural attenuation, Assistant degradation.