Assisted dissipation of a mix of PAHs in contaminated soils: effect of soil type and availability enhancers

Abstract

A remediation strategy using three non-toxic availability enhancers (two cyclodextrins and a rhamnolipid biosurfactant) was applied to various soils artificially contaminated with a mix of 14 Polycyclic Aromatic Hydrocarbons (PAHs) considered priority pollutants (from 3 to 6 rings). The high number of experimental factors (soil type, availability enhancers and incubation time) allowed to conduct a multivariate statistical analysis. Principal Component Analysis separated the studied PAHs in 3 groups, in relation with their molecular weight and Kow. The first principal component (PC1) was related with lower molecular weight PAHs, those with lower Kow and that have shown a high dissipation rate with final negligible contents. In this way, PC1 was related with the PAHs dissipated during the remediation process, and accordingly, the effect of incubation time was significantly associated to PC1, with decreasing values whereas time increases. Even more, this component was able to clearly separate the RAMEB (ramdomized methyl-β-cyclodextrin) from the other availability enhancers used. Otherwise, the second principal component was correlated with the higher molecular weight PAHs (5 and 6 rings) and was able to separate soils with different characteristics. The third principal component grouped two PAHs with intermediate molecular weight and more erratic dissipation pattern.