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

Abstract

A multidisciplinary three-step methodology is being developed to diagnose the extent and type of petroleum pollutants and resulting technological approaches to restore a contaminated site. At first, the site was delimitated and its zones identified by using remote sensors. An area of 307 ha considered of major importance to the national Mexican oil company, Petróleos Mexicanos (PEMEX), was identified. 75% of total analyzed soil samples ranged between 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 identification 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 seed germination efficiency and growth rate. Since microbial consortia isolated from C. laxus rhizosphere were able todegrade up to 70% of TPH in 30 days laboratory cultures, a phytoremediation-reforest alternative was finally proposed to PEMEX. In a third step, the construction of a pilot plant in situ is now in course wherein both treatability studies and reforest strategies are being developed.

Identification of Petroleum Resistant Plants and Rhizospheral Fungi for Phytoremediation of Petroleum Contaminated Soils

“…The findings in this study indicated that amounts of petroleum pollution in the non-vegetated soils are about three times more than vegetated soils. Our results are in accordance with some prior researches on other plant species in tropical regions 4),5), 19) and desert regions 5),20), 21) . Since phytoremediation of a petroleum-contaminated soil is mainly based on biodegradation in the rhizo sphere 12) , rhizospheral fungi are one of the most impor tant factors.…”

Effect of soil contaminated by diesel oil on the germination of seeds and the growth of Schinus terebinthifolius Raddi (Anacardiaceae) Seedlings

“…These results clearly indicated that the longer the time between the contamination and planting, the more efficient was the germination of S. terebinthifolius seeds. Similar results were found by Bossert and Bartha (1985), who registered low germinability of corn seeds in the soil contaminated by the crude oil, and by Gallegos-Martínez et al (2000), who found a reduction in the germination between 30 and 90% in the tropical native Mexican species subjected to soil contaminated with crude oil. Adam and Duncan (2002) also observed that the degree of alteration in germination of the seeds in gramineous, herbaceous and leguminous plants was affected by the amount of time that passed after the contamination.…”

Relationship between geomorphology and contamination with weathered hydrocarbons in an old river levee/marsh association

“…The average concentration of total petroleum hydrocarbons in the superficial stratum in these samples was 13,400 mg/kg, of which 73 % is heavy range and 27 % is mid-range and a trace of low range hydrocarbons was also found (Table 1) , 2003). This is in agreement with the results from a characterization that was done on hydrocarbons near the refinery several years ago in which 32.4 % of the hydrocarbons were asphaltenes, 39.8 % aliphatics, 18.9 % aromatics and 9.1 % polar compounds (Gallegos-Martínez et al, 2000;SEMARNAT, 2004). Thirteen of the 17 sampling points (76 %) were in or on the edge of the low, marshy, inter-levee areas in the property (Fig.…”

“…Th is property is less than 2 km to the North-East of the oldest and largest petroleum refinery in Latin America. Evaluations of adjacent and nearby areas have shown the soil to be highly contaminated (Gallegos-Martínez et al, 2000).…”

“…García-López et al (2006) analyzed the relation between vegetal communities growing in different type of soils and the presence of hydrocarbons, finding that most of the spills were located in mangrove and others areas covered by native plants principally belong to Poaceae, Cyperaceae and Fabaceae plants families. In the area studied soil hydrocarbon content and distribution, as well as floristic description has been previously reported (Gallegos-Martínez et al, 2000). However, information about the geomorphology and their influence in the hydrocarbon distribution is limited.…”