Phytoremediation of a highly creosote-contaminated soil by means of Salix viminalis
The aims of this study were to investigate whether Salix viminalis could grow in a highly creosote contaminated soil and, if so, whether the introduction of the plant enhanced the dissipation of polycyclic aromatic hydrocarbons (PAHs). The purpose was also to examine whether inoculation of two di...
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| Formato: | Otro |
| Lenguaje: | sueco Inglés |
| Publicado: |
2006
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| Materias: | |
| Acceso en línea: | https://stud.epsilon.slu.se/11872/ |
| Sumario: | The aims of this study were to investigate whether Salix viminalis could grow in a highly
creosote contaminated soil and, if so, whether the introduction of the plant enhanced the
dissipation of polycyclic aromatic hydrocarbons (PAHs). The purpose was also to
examine whether inoculation of two different bacterial strains further enhanced the
decrease of the contaminant. The experiment was conducted in a greenhouse during ten
weeks. The soil was collected at a former wood impregnation site belonging to the
Swedish railway administration, in Krylbo, Sweden. The experiment comprised two
different levels of PAH contaminated soil, the creosote soil used as such or diluted with
an arable soil (1:1). The main PAHs studied in this experiment were phenanthrene,
anthracene, fluoranthene, pyrene and benzo[a]pyrene. The soil samples were extracted
with toluene and analysed by GC-MS. Microbial analyses were made to measure the
number of extracted and cultivable bacteria (CFU/g soil) and dominating bacteria were
tested for gram, fluorescence and oxidase reactions. The plants were infected by some
bacterial disease which probably was an inherent infection of the cuttings and the number
of "healthy" plants was reduced by 2/3 in both the creosote soil and the diluted soil. The
initial PAH concentrations were very high, particularly for fluoranthene and pyrene.
Some PAH degradation occurred in pots without plants, but the dissipation of all studied
PAHs was enhanced in the presence of Salix viminalis and also the reduction of more
recalcitrant compounds such as benzo[a]pyrene was impressive. In the presence of plants
the PAH compounds were reduced in the creosote soil by 67 %, 79%, 77% and 43 % for
anthracene, fluoranthene, pyrene and benzo[a]pyrene respectively compared to the initial
values and by 61 %, 66%, 79% and 30% in the mixed soil. For all studied PAHs the
concentrations in the rhizosphere soil were found to be greater than in the bulk soil and
this could probably be explained mostly by the movement of compounds from the
surrounding soil into the rhizosphere, but partly also by an increased solubility. The
results indicate that the introduction of the inocula was not succesful, but due to the
inadequate number of pots with "healthy" plants no conclusions could be drawn. The
microbial analyses showed a significantly higher number of cultivable bacteria per gram
of soil in treatments with plants both compared to the initial soil and the treatments
without plants. |
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