Global budget and atmospheric degradation of levoglucosan and implications for its use as a biomass burning tracer

Abstract:

We used a global chemical transport model (GEOS-Chem) to quantify the global budget and atmospheric degradation of levoglucosan and compared the results to measurements, with the goal of quantifying the impacts of chemical degradation on the use of levoglucosan as a tracer for biomass burning emission. Global sources of levoglucosan included open fire biomass burning (1.754 Tg yr ^-1) and biofuel emission (2.055 Tg yr ^-1). Global sinks of levoglucosan included homogeneous aqueous oxidation and heterogeneous oxidation, as well as dry and wet deposition, resulting in a global lifetime of approximately 15 days. The simulated seasonal levoglucosan concentrations, when atmospheric degradation was included in the model, reproduced the observed global concentration gradient from near-source to remote sites. The atmospheric degradation of levoglucosan contributed to the decreasing levoglucosan to OC ratio (L/OC) and levoglucosan to K⁺ (L/K⁺) ratio from near-source to remote sites. Finally, we developed a simple parameterization to account for the degradation of levoglucosan in the use of levoglucosan as a tracer for biomass burning emissions.