Plant tolerance to diesel minimizes its impact on soil microbial characteristics during rhizoremediation of diesel-contaminated soils

• Published in: The Science of the total environment 2011-09, Vol.409 (19), p.4087-4093
• Main Authors: Barrutia, O., Garbisu, C., Epelde, L., Sampedro, M.C., Goicolea, M.A., Becerril, J.M.
• Format: Article
• Language: English
• Subjects: Applied sciences; Biodegradation, Environmental; Biological and medical sciences; Biotechnology; Communities; Contamination; Decontamination. Miscellaneous; Diesel; diesel fuel; Diesel fuels; Earth sciences; Earth, ocean, space; Engineering and environment geology. Geothermics; Environment and pollution; Exact sciences and technology; Fundamental and applied biological sciences. Psychology; Gasoline; germination; grassland soils; greenhouses; Health; Industrial applications and implications. Economical aspects; Lolium - growth & development; Lolium - metabolism; Lolium - physiology; Lolium perenne; microbial activity; Microorganisms; Miscellaneous; n-alkanes; photosystem II; plant growth; Plant Roots - growth & development; Plant Roots - metabolism; Plant Roots - physiology; Plant Shoots - growth & development; Plant Shoots - metabolism; Plant Shoots - physiology; polluted soils; Pollution; Pollution, environment geology; Pots; relative humidity; Rhizome - chemistry; Rhizome - metabolism; rhizosphere; seedlings; Soil (material); Soil - chemistry; Soil and sediments pollution; Soil microbial community; Soil Microbiology; soil microorganisms; Soil Pollutants - metabolism; Soil pollution; Soil quality; Trifolium - growth & development; Trifolium - metabolism; Trifolium - physiology; Trifolium repens
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2011.06.025

Soil contamination due to petroleum-derived products is an important environmental problem. We assessed the impacts of diesel oil on plants ( Trifolium repens and Lolium perenne) and soil microbial community characteristics within the context of the rhizoremediation of contaminated soils. For this purpose, a diesel fuel spill on a grassland soil was simulated under pot conditions at a dose of 12,000 mg diesel kg − 1 DW soil. Thirty days after diesel addition, T. repens (white clover) and L. perenne (perennial ryegrass) were sown in the pots and grown under greenhouse conditions (temperature 25/18 °C day/night, relative humidity 60/80% day/night and a photosynthetic photon flux density of 400 μmol photon m − 2 s − 1 ) for 5 months. A parallel set of unplanted pots was also included. Concentrations of n-alkanes in soil were determined as an indicator of diesel degradation. Seedling germination, plant growth, maximal photochemical efficiency of photosystem II (F v/F m), pigment composition and lipophylic antioxidant content were determined to assess the impacts of diesel on the studied plants. Soil microbial community characteristics, such as enzyme and community-level physiological profiles, were also determined and used to calculate the soil quality index (SQI). The presence of plants had a stimulatory effect on soil microbial activity. L. perenne was far more tolerant to diesel contamination than T. repens. Diesel contamination affected soil microbial characteristics, although its impact was less pronounced in the rhizosphere of L. perenne. Rhizoremediation with T. repens and L. perenne resulted in a similar reduction of total n-alkanes concentration. However, values of the soil microbial parameters and the SQI showed that the more tolerant species ( L. perenne) was able to better maintain its rhizosphere characteristics when growing in diesel-contaminated soil, suggesting a better soil health. We concluded that plant tolerance is of crucial importance for the recovery of soil health during rhizoremediation of contaminated soils. ► Plant presence stimulates microbial activity in both diesel-contaminated and non-contaminated rhizosphere soils. ► Impact of diesel on rhizosphere microbial characteristics is lower in Lolium perenne than in Trifolium repens planted soils. ► Lolium perenne is more tolerant to diesel and shows a higher potential for diesel rhizoremediation than Trifolium repens.