Investigating PM10 episodes using levoglucosan as tracer
Monteiro, Alexandra; Gouveia, Sónia; Scotto, Manuel; Sorte, Sandra; Gama, Carla; Gianelle, Vorne; Colombi, Cristina; Alves, Célia
Air Quality, Atmosphere & Health, 11 (2018), 61-68
The present study aims to investigate the role/contribution of residential combustion (using levoglucosan as a tracer of biomass combustion) during PM10 episode days registered over the Porto urban area (Portugal), in order to support air quality plans that need to be developed for this particular region. The levoglucosan and PM10 concentration values, together with the meteorological conditions (namely temperature), measured during an experimental field campaign performed in 2013, were used in this study. To this end, a wavelet-based approach is applied to (a) better quantify the coherence and dependency of these variables and; (b) assess the strength of the connection between the two pollutants species (PM and levoglucosan) at different time scales. Results evidenced a high coherence/dependency between PM10 and levoglucosan values for the episodes selected (periods with exceedances of the PM10 limit values), suggesting the contribution of biomass combustion sources. The highest coherence (normalised co-variance) is observed for the winter episodes and time periods of 5-10 days, which is related to the duration of the episodes selected. The summertime episode, which exhibits a negligible observed correlation between temperature and levoglucosan, is explained by the influence of forest fires that occurred within this period and region.