Assessment Of Tropical Grasses And Legumes For Phytoremediation Of Petroleum-Contaminated Soils

Abstract

Phytoremediation is a promising technology for the clean-up of petroleum-contaminated soils, especially in the tropics where climatic conditions favour plant growth and microbial activity and where financial resources can be limited. The objective of this work was to identify tropical plant species from the eastern savannahs of Venezuela suitable for this technology. Three legumes (Calopogonium mucunoides, Centrosema brasilianum, Stylosanthes capitata) and three grasses (Brachiaria brizantha, Cyperus aggregatus, Eleusine indica) were tested for their ability to stimulate microbial degradation in soil contaminated with 5% (w/w) of a heavy crude oil. In greenhouse experiments, plant biomass production and oil dissipation (total oil and grease, and fraction composition) were analysed after 90 and 180 days incubation. Although previously tested on their tolerance to oil contamination, the legumes died within six to eight weeks. The grasses showed reduced biomass production under the influence of the contaminant. Relative growth rates were higher in contaminated soil indicating a delay in plant growth patterns and development. Soil planted with B. brizantha and C. aggregatus showed a significantly lower oil concentration than non-vegetated soil. Furthermore, a positive correlation between root biomass production and oil degradation was found. Concentration of saturated hydrocarbons was always lower in planted than in unplanted soil. B. brizantha also caused a considerable reduction of aromatics. Based on these results, B. brizantha is recommended for follow-up investigations which could further develop the application of phytoremediation of petroleum-contaminated soils in the tropics.

Biodegradation of Petroleum Hydrocarbons in a Tropical Ultisol Using Legume Plants and Organic Manure

“…It is also believed that the plants may have participated in biodegradation of hydrocarbons via support of symbiotic root-associated micro-organisms which was earlier reported by Stamps et al (1994) and Ensley et al (1997). The Gliricidia and Leucaena showed better promise than Galapogonium in reducing RTPHs in the soil, indicating that different species of plants have varying effects on rhizosphere micro-organisms and on hydrocarbon degradation activities in the soil (Merkl et al, 2005). As low as 14,936 mg kg -1 total hydrocarbons, representing 30% was degraded naturally by the native soil microorganisms after 36 months ( …”

“…The treatment technologies are often developed and evaluated in order to conform to the regulatory demands and International standards (Lee & Banks, 1993). However, many of the standard treatment methods available for cleaning-up soils contaminated with petroleum hydrocarbons have been limited in their application, are prohibitively expensive, or may be only partially effective (Merkl et al, 2005). The high cost associated with a number of these methods, has also been a major limitation to the sustainability of such methods (Kelly et al, 1992;Van Gestel et al, 1992).…”

Physical Properties And Maize Production In A Spent Oil-Contaminated Soil Bioremediated With Legumes And Organic Nutrients

“…The positive role of Gliricidia and Leucaena spp. in enhancing the macro-porosity could be attributable to their ability to improve the soil organic matter (SOM) content (Table 6) and the influence of their root exudates on the rhizosphere soil (Merkl et al, 2005, MolinaBarahona et al, 2004. A combination of poultry manure with Gliricidia spp, Calapogonuim spp.…”

“…However, the major focus has been on heavy metal attenuation and other chemical properties (Merkl et al, 2005;Harayama et al, 2004;Gallizia et al, 2003). Information regarding the use of some legumes and organic nutrient to improve the physical properties of oil-contaminated soil, with a view to making it available for crop production, is limited.…”

An Evaluation of Edible Plant Extracts for the Phytoremediation of Lead Contaminated Water

“…Phytoremedia-tion technique has shown promise in the mitigation of organic contaminants [27][28][29], and petroleum hydrocarbons [30]. However, the technologies for heavy metal contaminated soil has met mixed success because of cost prohibitive ex-situ processes that require excavation and removal [31,32].…”