ABSTRACT
A phytoremediation growth chamber study was conducted to evaluate the contribution of soil microbial diversity to the contaminant degradation. Target contaminant removal from soil was assessed by monitoring concentrations of polycyclic aromatic hydrocarbons (PAHs), along with changes in the bacterial community structure over a time period of 10 months in the presence of tall fescue (Festuca arundinacea). Enhanced degradation of PAHs was observed in rhizosphere soil, with a maximum reduction in pyrene at a rate 36% higher than that noted for the unvegetated control. The dissipation of < 4-ring PAHs, 4-ring PAHs, and > 4-ring PAHs in unvegetated soil was 70%, 54%, and 49% respectively, whereas a higher dissipation rate was observed in tall fescue treated soil of 78%, 68%, and 61% at the end of the study. Microbial enumeration results showed greater total bacterial numbers and PAH-degrading bacteria in rhizosphere soil when compared to unvegetated soil. The results from the terminal restriction fragment length polymorphism (T-RFLP) analysis indicated that there was a shift in the rhizosphere bacterial community during the phytoremediation process.
Notes
∗CEC, cation exchange capacity.
∗Letters after value indicate significant difference between vegetated and unvegetated means for each PAH based on a two-sample t test with α of .05. If the letters are different, there is a significant difference between the pairs.
∗Letters after value indicate significant difference between vegetated and unvegetated means for each PAH based on a two-sample t test with α of .05. Different letters indicate a significant difference between the pairs.