Correlations between optical, chemical and physical properties of biomass burn aerosols

Aerosols generated from burning different plant fuels were characterized to determine relationships between chemical, optical and physical properties. Single scattering albedo (omega) and Angstrom absorption coefficients (alpha(ap)) were measured using a photoacoustic technique combined with a reciprocal nephelometer. Carbon-to-oxygen atomic ratios, sp(2) hybridization, elemental composition and morphology of individual particles were measured using scanning transmission X-ray microscopy coupled with near-edge X-ray absorption fine structure spectroscopy (STXM/NEXAFS) and scanning electron microscopy with energy dispersion of X-rays (SEM/EDX). Particles were grouped into three categories based on sp(2) hybridization and chemical composition. Measured w (0.4 - 1.0 at 405 nm) and alpha(ap) (1.0 - 3.5) values displayed a fuel dependence. The category with sp(2) hybridization > 80% had values of omega (< 0.5) and alpha(ap) (similar to 1.25) characteristic of light absorbing soot. Other categories with lower sp(2) hybridization (20 to 60%) exhibited higher w (> 0.8) and alpha(ap) (1.0 to 3.5) values, indicating increased absorption spectral selectivity. Citation: Hopkins, R. J., K. Lewis, Y. Desyaterik, Z. Wang, A. V. Tivanski, W. P. Arnott, A. Laskin, and M. K. Gilles (2007), Correlations between optical, chemical and physical properties of biomass burn aerosols, Geophys. Res. Lett., 34, L18806, doi: 10.1029/2007GL030502.