The extent of non-extractable residue formation was found to increase with time and HPCD concentration. At 42 d ageing, aqueous HPCD extractable phenanthrene decreased with increasing HPCD concentration, while the extent of non-extractable residue formation increased with increasing HPCD concentration. The presence of HPCD in the soils enhances loss of phenanthrene from the soil with ageing. High concentrations of HPCD appear to enhance the ageing process, while lower concentrations may retard it. Microbial bioavailability of phenanthrene is lowest at high concentrations of HPCD These results show that HPCD application has potential as a treatment for soils contaminated with organic compounds, as a method of either enhancing or retarding the ageing process, depending on the concentration of the application.
Further work is required to optimise treatment conditions.