Diagnostic and resulting approaches to restore petroleum-contaminated soilin a Mexican tropical swamp

A multidisciplinary three-step methodology is being developed to diagnose t he extent and type of petroleum pollutants and resulting technological appr oaches to restore a contaminated site. At first, the site was delimitated a nd its zones identified by using remote sensors. An area of 307 ha consider ed of major importance to the national Mexican oil company, Petroleos Mexic anos (PEMEX), was identified. 75% of total analyzed soil samples ranged bet ween 10-50,000 ppm of total petroleum hydrocarbons (TPH) and 25% between 50 ,000 and 434,000 ppm. Aliphatic and asphaltene groups were predominant and technological alternatives were proposed. In a second phase the identificat ion of native botanical and microbial capabilities to biodegrade pollutants was achieved. Three native botanical species were selected for greenhouse studies: Cyperus laxus showed low sensitivity to TPH resulting in higher se ed germination efficiency and growth rate. Since microbial consortia isolat ed from C, laxus rhizosphere were able to degrade up to 70% of TPH in 30 da ys laboratory cultures, a phytoremediation-reforest alternative was finally proposed to PEMEX. In a third step, the construction of a pilot plant in s itu is now in course wherein both treatability studies and reforest strateg ies are being developed.