Impact of arbuscular mycorrhizal fungi on phytoremediation of hydrocarbon polluted soils

Details

Supervisors

Declerck, Stephan ; Garces Ruiz, Monica Cristina

Faculty

Faculté des bioingénieurs

Degree label

Master [120] : bioingénieur en sciences agronomiques, à finalité spécialisée

Abstract

Accidental spills of crude oil or its derivatives occur frequently all over the world, leading to long term harmful consequences for both the environment and human health. Developing cost-effective and environmentally-friendly remediation methods is crucial. Combined approaches including phytoremediation have demonstrated interesting potential, and the use of AMF to enhance phytoremediation effectiveness has been progressively considered. In greenhouses, two AMF communities were studied to assist Medicago sativa in phytoremediation of a diesel polluted substrate. The first community was composed of three species isolated from non-polluted environment: Rhizophagus irregularis, Acaulospora spinosa and Archaeospora schenckii. The second community was composed of strains isolated from weathered crude oil ponds in the Amazon region of Ecuador. The strains, identified as a Rhizophagus sp. and two Acaulospora sp., were described by spore taxonomy. Mats of mature and mycorrhized M. sativa were developed and transferred on a polluted substrate for three months. The effect of these two communities was analyzed on the plant oxidative stress, the plant shoot and root biomasses, and the degradation rate of diesel. With the community from non-polluted environment, a positive correlation was observed between AMF total colonization and the plant root/shoot ratio in pots contaminated by diesel. AMF stimulated plant investment into the roots rather than the shoots, suggesting an interesting feature to improve plant tolerance to petroleum stress and to remediate larger volumes of soil. In addition, similar to lower degradation rates were observed in presence of M. sativa in comparison with pots without any vegetal cover, suggesting a stabilization of the pollutant by the plants, limiting diesel volatilization and leaching. Longer-term bioremediation experiments with AMF might be needed to observe better pollutant degradation via rhizostimulation. In this experiment, propagation of the AMF communities, and especially the strains from polluted environment, has proved to be a delicate task. Improved inoculation methods are therefore necessary and further research about the potential of these AMF communities should be considered.