Observation of elevated fungal tracers due to biomass burning in the Sichuan Basin at Chengdu City, China.

Fungal material (i.e., spores and fragments) is an important component of atmospheric aerosols. In order to examine the variability of fungal abundance in fine particles (PM(2.5)) during a biomass burning season, an intensive measurement campaign was conducted in the Sichuan Basin at Chengdu, a megacity in southwest China, in spring 2009. The aerosol samples were analyzed for carbonaceous species, including molecular tracers for biomass burning and fungal material, and water soluble ions. The results were interpreted with the help of principle component analysis, fire count maps, and the WRF model. Elevated concentrations of arabitol and mannitol were found with average concentrations of 21.5±16.6 ng m(-3) and 43.9±19.3 ng m(-3), respectively, which were unexpectedly higher than those measured in fine particles in any other study reported previously. Even higher concentrations were observed in cases with simultaneous enhancements in the biomass burning tracers levoglucosan and K(+). In the case of influence by pollution plumes from biomass burning regions, the fungal tracer concentrations reached maximum values of 79.6 ng m(-3) and 121.8 ng m(-3), coinciding with peak levels of levoglucosan and K(+). Statistically significant correlations were found between the simultaneously observed fungal tracers (arabitol and mannitol) and biomass burning tracers (levoglucosan and K(+)), suggesting that these species were emitted by co-located sources, and hence the elevated fungal tracers were likely associated with biomass burning activities.