Chemical and isotopic characterization of carbonaceous aerosol particles from burning of different fuels

Abstract

Emissions from burning hardwoods, softwoods, crops, and coal were analysed for stable carbon isotopic composition and organic aerosol chemistry. Hardwood emissions showed the most negative total carbon δ13C values (from –25.2 ‰ to –30.5 ‰), while softwoods emissions ranged from –23.5 ‰ to –26.3 ‰. The organic carbon (OC) desorbed at 350 °C had lower δ13C value compared to OC desorbed at 200 °C temperature by -0.9 ± 0.4 ‰ (average +/- 1 std). The δ13C values of elemental carbon (EC) are systematically lower than those of total carbon (on average –0.7 ‰) across nearly all combusted fuels. Coal emissions exhibited δ13C values within a narrow range (–24.9 ± 0.4 ‰; 1σ std deviation) across all carbon fractions. Overall, the emitted particles have similar isotopic signatures (within 0 ± 1 ‰) as the fuels for most species with some exceptions. OC/EC ratios vary in a wide range (from 3.7 to 73.9). Thermal desorption PTR–MS analysis revealed that biomass burning aerosols were dominated by oxygenated hydrocarbons (74–85 %). Ten major compounds, out of the 723 identified from biomass and coal combustion, contribute up to 30 % of the total OA mass fraction for the individual fuels. PTR–MS and IRMS data analysis revealed that four cellulose tracers peaked at 200 °C and five lignin tracers peaked at 350 °C desorption temperature, explaining the depletion of13C at the 350 °C temperature step. This article highlights the multifaceted nature of aerosols from biomass burning, emphasizing the need for integrated research efforts.