Potential of vetiver (Vetiveria zizanioides(L.) Nash) for phytoremediation of petroleum hydrocarbon-contaminated soils in Venezuela

Abstract

Venezuela is one of the largest oil producers in the world. For the rehabilitation of oil-contaminated sites, phytoremediation represents a promising technology whereby plants are used to enhance biodegradation processes in soil. A greenhouse study was conducted to determine the tolerance of vetiver (Vetiveria zizanioides (L.) Nash) to a Venezuelan heavy crude oil in soil. Additionally, the plant's potential for stimulating the biodegradation processes of petroleum hydrocarbons was tested under the application of two fertilizer levels. In the presence of contaminants, biomass and plant height were significantly reduced. As for fertilization, the lower fertilizer level led to higher biomass production. The specific root surface area was reduced under the effects of petroleum. However, vetiver was found to tolerate crude-oil contamination in a concentration of 5% (w/w). Concerning total oil and grease content in soil, no significant decrease under the influence of vetiver was detected when compared to the unplanted control. Thus, there was no evidence of vetiver enhancing the biodegradation of crude oil in soil under the conditions of this trial. However, uses of vetiver grass in relation to petroleum-contaminated soils are promising for amelioration of slightly polluted sites, to allow other species to get established and for erosion control.

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

“…(Poaceae), respectively. Brandt et al (2006) found evidence that the reduced growth and biomass found in Vetiveria zizanioides (L.) Nash (Poaceae) in the contaminated soil was related to the nutrients content. Daniel-Kalio and Pepple (2006) found that the time interval between the contamination and the establishment of seedlings affected the biomass of Commelina benghalensis L. (Commelinaceae).…”

“…The same substance can induce different effects in different species, and conversely, the same symptoms can arise from exposure to different substances (Baker, 1970). The most common and important symptoms observed in the plants contaminated with oil and its byproducts include the erosion of the epicuticular wax (Baker, 1970), degradation of chlorophyll (Baker, 1970;Malallah et al, 1996 and, alterations in the stomatal mechanism (Baker, 1970), reduction in photosynthesis and respiration (Baker, 1970), increase in the production of stress-related phytohormones (Larcher, 2000), accumulation of toxic substances or their byproducts in vegetal tissue (Baker, 1970), decrease in size and less production of biomass (Proffitt et al, 1995;Green et al, 1996;Kuhn et al, 1998;Brandt et al, 2006;Daniel-Kalio and Pepple, 2006;Adenipekun et al, 2008). In some cases after an oil spill, an increase in the production of biomass and in the growth and development of some species can be observed.…”

Regulation of functional activities and essential oil production in Vetiveria zizanioides L. Nash after γ-irradiated sodium alginate elicitation

“…The roots serve the dual purpose of sustaining the environment as they form an intertwined network in the soil, making the soil environment suitable for land rehabilitation. Vetiver roots are also known to regulate soil and water conservation and remediate polluted sites (Brandt et al, 2006;Antiochia et al, 2007). Moreover, the roots of vetiver also synthesize a specific essential oil (EO), which is highly valued for its aromatic and pharmaceutical properties.…”

Microbe assisted phytoremediation of oil sludge and role of amendments: a mesocosm study

“…Also Chang and Richard (1998) have reported enhanced oil remediation by addition of bulking agent. Brandt et al (2006) during their research carried out on phytoremediation of petroleum contamination found that Vetiver was efficient in degrading the contaminant. This study resulted in degradation of oil and TPH compounds by using all possible technologies implemented till date by making use of plant (phytoremediation), microbial consortium (bioremediation), addition of bulking agent and nutrient (biostimulation) together, and hence has proved its efficiency over conventional remediation technologies.…”

“…3). Brandt et al (2006) has mentioned in his study that petroleum hydrocarbons have high carbon content but poor nitrogen and phosphorus content, and microbes use up the available nutrients during mineralization of hydrocarbons. Hence, supplementation of nutrients helps in increasing the degradation rate.…”