Flux measurements of benzene and toluene from landfill cover soils

Carbon dioxide and CH 4, C6H6 and C7H8 fluxes from the soil cover of Case Passerini landfill site (Florence, Italy) were measured using the accumulation and static closed chamber methods, respectively. Results show that the CH4/CO2, CH4/ C 6H6 and CH4/C7H8 ratios of the flux values are relatively low when compared with those of the ‘pristine’ biogas produced by degradation processes acting on the solid waste material disposed in the landfill. This suggests that when biogas transits through the cover soil, CH4 is affected by degradation processes activated by oxidizing bacteria at higher extent than both CO2 and mono-aromatics. Among the investigated hydrocarbons, C6H6 has shown the highest stability in a wide range of redox conditions. Toluene behaviour only partially resembles that of C6H6, possibly because de-methylation processes require less energy than that necessary for the degradation of C6H6, the latter likely occurring via benzoate at anaerobic conditions and/or through various aerobic metabolic ...