Targeting sorbed PAHs in historically contaminated soil - Can laccase mediator systems or Fenton's reagent remove inaccessible PAHs?

This laboratory study investigates the potential of two innovative laccase-mediator systems for removing PAHs from historically contaminated field soil and focuses on the treatment effect on the accessible and desorption resistant PAH fraction. Laccase degraded accessible PAHs when applied in combination with the mediator TEMPO (up to 24 % within 48 h). The mediator HBT did not induce degradation but mobilized desorption resistant PAHs from high affinity sorption sites via a competitive sorption mechanism.

Atmospheric carbonation reduces bioaccessibility of PAHs in industrially contaminated soil.

Sorptive Bioaccessibility Extraction (SBE) was used to monitor changes in accessibility of polycyclic aromatic hydrocarbons (PAHs) during storage of historically contaminated alkaline soil (Σ US EPA 16 + 2 further PAHs: 2452 ± 69 mg kg, n = 3). While total concentrations of PAHs were rather stable during storage for 561 days at 4 °C, PAH accessibility declined by 95% due to atmospheric carbonation. The formation of carbonates was evidenced by an increase of inorganic soil carbon and by carbonate coatings on black soil particles (SEM-EDX) that could be dissolved by providing neutral to acidic soil conditions.

Enhanced Accessibility of Polycyclic Aromatic Hydrocarbons (PAHs) and Heterocyclic PAHs in Industrially Contaminated Soil after Passive Dosing of a Competitive Sorbate.

To assess the exposure to polycyclic aromatic hydrocarbons (PAHs) it is important to understand the binding mechanisms between specific soil constituents and the organic pollutant. In this study, sorptive bioaccessibility extraction (SBE) was applied to quantify the accessible PAH fraction in industrially contaminated soil with and without passive dosing of a competitive sorbate. SBE experiments revealed an accessible PAH fraction of 41 ± 1% (∑16 US EPA PAHs + 5 further PAHs).