Removal of Two High Molecular Weight PAHs from Soils with Different Water Content

Polycyclic aromatic hydrocarbons (PAHs) such as benz[a]anthracene (BA) and dibenz[a,h]anthracene (DBA), which are considered toxic, are frequently found in contaminated soils in Mexico. A laboratory-scale study monitored the degradation of the mixture of these two PAHs in three soils from different Mexican states (Tabasco, Morelos and Veracruz), each with different organic matter content, particle size distribution and incubated under different water content conditions. The hydrocarbons were extracted using microwave digestion and quantified by GC/MS. The removal of the PAHs, the growth of aerobic bacteria and microbial activity were determined in soil samples with and without a bacterial growth inhibitor (HgCl₂). The conclusion is that more than 90% of both contaminants was removed from the three soils, independently of the soil water content or the application of a bacterial growth inhibitor. Biological properties of the soils showed changes at the end of the experiment, but the results of the removal of PAHs were similar in the three soils.