On the sequestration of polycyclic aromatic hydrocarbons in aged artificial soil

The fate of polycyclic aromatic hydrocarbons is a major environmental concern that has attracted much attention in the current literature. The physicochemical properties of contaminants, along with soil characteristics and aging, translate into unusual sorption that leads to high sequestration and low bioavailability even in artificial systems. In the present study, fresh (non-sterile) and aged (sterile) artificial soils (sand-perlite 1:1 v/v) were characterized and spiked (hexadecane, phenanthrene and pyrene 2:1:0.5 w/w) to evaluate extractability. Hydrocarbons extraction differed for sand and perlite in fresh samples, on the contrary, the artificial aging process affected equally the extraction in the artificial soil components. In the artificial soil, the extractability of hexadecane and phenanthrene were 80 and 60%, respectively, in fresh samples, but for both hydrocarbons, it was only 20% in aged samples. Pyrene extractability was not affected by the components of the artificial soil or by aging, and this may be related to an in-situ crystallization process. The characteristics of the soil and its contaminants, coupled with long-term interactions, led to the formation of non-extractable residues, also known as sequestered contaminants. This study expands the current knowledge about the use of artificial materials for contaminants' environmental fate evaluation and should serve as motivation for further experimental and theoretical research on this subject.