Comparative dissipation of anthracene and phenanthrene in a pristine typic Hapludoll soil

Polycyclic aromatic hydrocarbons (PAHs) are of great environmental concern due to their widespread occurrence and persistence. Anthracene and phenanthrene (C14H10) are two priority pollutants that are found in high concentrations in PAHs-contaminated surface soils. The objective of this study was to analyze the capability of endogenous soil microorganisms of a pristine soil of the Pampas region, Argentina, to dissipate two isomers: anthracene and phenanthrene. Nutrient availability and the effects of ryegrass (Lolium perenne L.) on these PAHs' dissipation were also evaluated. After 100 days, both contaminants were significantly degraded in root-free soils by autochthonous microorganisms. L. perenne significantly enhanced microbial degradation. The dissipation of both pollutants in the rhizosphere was accompanied by higher values of total bacteria counts at the end of the experimental period. No biostimulation effect was observed. In all cases, the dissipation of phenanthrene was significantly higher than anthracene. These results point to the important role of indigenous PAH degrading microorganisms, even present in a non-polluted soil.