Using levoglucosan as a molecular marker for the long-range transport of biomass combustion aerosols

Samples of ambient particulate matter (PM10) collected during a regional ha ze episode are analyzed for the molecular marker levoglucosan (1,6-anhydro- beta -D-glucopyranose) to track biomass-combustion generated aerosol. The p article samples were collected as part of an increased monitoring effort to measure the effect of emissions from biomass fires in Mexico and Central A merica on ambient particle concentrations in Texas. Atmospheric concentrati ons of levoglucosan quantified from PM10 samples collected at 9 sites in Te xas vary from 0.2 to 1.2 mug m(-3). Levoglucosan concentrations are highest at border and coastal locations, where it represents between 1.1 and 1.3% of the total PM10 mass concentrations measured. To he used as a tracer for the long-range transport of biomass aerosol, levoglucosan must be conserved in transport from source to receptor and not be subject to atmospheric rea ctions that would selectively remove the marker. One possible reaction spec ific to levoglucosan, acid-catalyzed hydrolysis, is studied tinder conditio ns simulating the aqueous chemistry of atmospheric droplets. Results show n o degradation of levoglucosan over a period of 10 days. This stability is i ncorporated into the long-range transport analysis of biomass combustion du ring the haze episode to determine the relative impact of long-range transp ort of combustion aerosol and local sources on PM10 levels on inland locati ons.