Assessment of BTX concentrations near a petrol station using passive samplers
Résumé
A combined monitoring and dispersion modelling methodology was applied for assessing air quality related to concentration levels of benzene, toluene and xylenes (BTX) at three different levels of proximity to a petrol selected service Station: (I) next to the fuel pumps, (II) in the surrounding environment, and (III) m the background. A Gaussian dispersion model (CALINE4) was used for assessing the road traffic contribution to the local concentrations under different meteorological conditions. It was established that Stage 2 vapour recovery reduces BTX concentrations not only near the pumps but also in their surrounding environment. However, there is evidence that the efficiency of the System is wind speed dependent. The modelling Simulation of the worst case wind scenario revealed the significance of local traffic emissions. It was shown that the traffic contribution to the local BTX levels even from a single road in the vicinity of the Station can be, under certain conditions, higher than the contribution of the Station itself. Finally, after comparison with previous studies, the concentrations measured near the service station (which was situated in a rural environment) appear to be lower than those observed in busy street canyons in city centres. It can be concluded that although Stage 2 recovery System effectively reduces working VOC losses in service stations, it will only have a limited positive impact on local air quality if the service Station is located in a heavily polluted area.
Domaines
Sciences de l'environnement
Origine : Fichiers produits par l'(les) auteur(s)
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