Evidence of biomass burning aerosols in the Barcelona urban environment during winter time

Abstract: The influence of biomass burning (BB) aerosols, whether of regional or local origin, on fine aerosol levels in the Barcelona urban environment (Spain) was investigated. High-time resolved data on light-absorbing aerosols and inorganic tracers in PM2.5 were combined to this end during a dedicated sampling campaign carried out in winter 2011. The evaluation of PM inorganic components and equivalent black carbon evidenced that local-scale BB emissions were not detectable, whereas a source of K, different to vehicular traffic (road dust) and construction/demolition dust re-suspension, was detectable in the urban area. Source apportionment analysis evidenced the contribution from one source traced by S (62% of the source profile) and K (16% of the source profile), which was interpreted as regional-scale transport of secondary aerosols including BB contributions. The S/K ratio for this source (S/K = 4.4) indicated transport of the polluted air masses, as occurs from the rural areas towards the Barcelona urban environment. On average for the study period, the contribution of K-related aerosols from regional BB to PM2.5 levels in the urban environment was estimated as 1.7 μg/m3 as a daily mean, accounting for 8% of the PM2.5 mass during the winter period under study. The contribution from this source to urban aerosols should be lower on the annual scale. [Copyright &y& Elsevier]