Contribution of Microcosm and Respirometric Experiments to PAHs' Intrinsic Biodegradation in the Soil of a Former Coke Site

Microcosm and respirometric experiments were used to evaluate polycyclic aromatic hydrocarbons' (PAHs') intrinsic biodegradation in soil from a former coke site. The study was carried out in solid phase, over 12 months, at 20°C, in aerobic conditions. Microbial degradation activity in respirometry was assessed by monitoring the CO2 production and O2 consumption as well as by following the decrease in PAH content in the soil samples. PAHs' biodegradation patterns are very similar both in microcosm experiments and in respirometry. Respirometric experiments show CO2 production and O2 consumption over all biodegradation experiments, whereas no more loss of PAHs is measured after only a few weeks of experimentation. This indicates that monitoring only CO2 production or O2 consumption is not enough to assess PAHs' biodegradation. It seems that, after having degraded the most available PAHs, microbiota shift to other sources of carbon for their metabolism.