Flux measurements of benzene and toluene from landfill cover soils.
Carbon dioxide and CH(4), C(6)H(6) and C(7)H(8) 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 CH(4)/CO(2), CH(4)/C(6)H(6) and CH(4)/C(7)H(8) 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, CH(4) is affected by degradation processes activated by oxidizing bacteria at higher extent than both CO(2) and mono-aromatics. Among the investigated hydrocarbons, C(6)H(6) has shown the highest stability in a wide range of redox conditions. Toluene behaviour only partially resembles that of C(6)H(6), possibly because de-methylation processes require less energy than that necessary for the degradation of C(6)H(6), the latter likely occurring via benzoate at anaerobic conditions and/or through various aerobic metabolic pathways at relatively shallow depth in the cover soil where free oxygen is present. According to these considerations, aromatics are likely to play an important role in the environmental impact of biogas released into the atmosphere from such anthropogenic emission sites, usually only ascribed to CO(2) and CH(4). In this regard, flux measurements using accumulation and static closed chamber methods coupled with gas chromatography and gas chromatography-mass spectrometry analysis may properly be used to obtain a dataset for the estimation of the amount of volatile organic compounds dispersed from landfills.
Department of Earth Sciences, University of Florence, Florence, Italy. franco.tassi@unifi.it
Franco
F
Tassi
Giordano
G
Montegrossi
Orlando
O
Vaselli
Andrea
A
Morandi
Francesco
F
Capecchiacci
Barbara
B
Nisi
D001554:Benzene / Q000032:analysis*; D001673:Biodegradation, Environmental; D002245:Carbon Dioxide / Q000032:analysis; D052918:Environmental Restoration and Remediation; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods; D007558:Italy; D008697:Methane / Q000032:analysis; D012037:Refuse Disposal; D012987:Soil / Q000032:analysis; D012989:Soil Pollutants / Q000032:analysis* / Q000737:chemistry; D014050:Toluene / Q000032:analysis*; D018505:Waste Management; D014866:Waste Products / Q000032:analysis
D012987:Soil; D012989:Soil Pollutants; D014866:Waste Products; D002245:Carbon Dioxide; D014050:Toluene; D001554:Benzene; D008697:Methane