Univariate and multivariate characterization of heavy fuel oil weathering and biodegradation in soil

Polycyclic aromatic compounds (PACs) of petrogenic origin are widespread contaminants of the environment. We investigated the weathering and biodegradation of fuel oil PACs in microcosms that contained natural soil or natural soil primed by adding bioremediated soil to a 2% concentration. In the primed soil, lag-phases were shorter, and biodegradation was more pronounced. To describe PAC degradation, changes in the relative distribution of PACs and changes in isomer ratios, that are specific for biodegradation, were determined by univariate and multivariate techniques. A multivariate approach based on normalized areas or isomer ratios, in combination with principal component analysis, provided the most detailed description of weathering and biodegradation. In particular, the sequence of degradation of PACs was more transparent when using the multivariate approach. We also identified new diagnostic ratios of dimethylphenanthrenes for use in the study of moderately and severely biodegraded samples.