Unsubstituted polycyclic aromatic hydrocarbons and phenanthrene derivatives in wood waste

The study presents an investigation into the concentrations of polycyclic aromatic hydrocarbons (PAHs) and phenanthrene derivatives in bark-and-wood wastes (BWW) from sawmills following long-term storage (70 years), as well as an identification of the factors influencing their accumulation and toxicity. Elevated levels of PAHs and their derivatives were detected in the BWW profiles. Low-molecular-weight (LMW) PAHs exhibited a relatively uniform vertical distribution throughout the profiles of both cores. In deeper layers (below 12 m), the concentrations of high-molecular-weight (HMW) PAHs and their derivatives increased sharply. This accumulation is attributed to pedogenic processes occurring during waste decomposition under conditions of elevated temperature and humidity. Additionally, an inverse relationship was identified in the accumulation of PAHs and their derivatives in lower BWW layers. The elevated concentrations of HMW PAHs and derivatives observed in the upper section of Core 1 are likely associated with fire-related phenomena characteristic of BWW landfills. PCA analysis revealed a significant correlation between the accumulation of PAHs and derivatives and the pH and moisture content of the waste. Specifically, higher concentrations of the target compounds were detected under conditions of high moisture content and neutral pH. The lower layers of the BWW exhibited high toxicity; notably in Core 1, the total toxic equivalency concentration (TEQ) exceeded the maximum permissible concentration (MPC) of benzo[a]pyrene for soils by up to a factor of nine. Ecological risk assessments indicated the upper BWW layers pose a low risk to living organisms and natural ecosystems, whereas the lower layers presented a moderate risk.