Physio-Chemical Characterization of Particles Emitted from Harvesting Operations in Subtropical Sugarcane Production.

ABSTRACT Particulate matter (PM) of different sizes (PM10 and PM2.5) from biomass burning is one of the major contributors of ambient air pollution. The objective of this research was to characterize chemical composition and morphological features of the particles produced during harvesting events of sugarcane in Louisiana, USA. Particles were collected on quartz fiber filters during regular harvesting (RH) without biomass burning, combine harvest (CH) after standing burning, standing burn (SB) and ground burn (GB) of sugarcane biomass residues. The collected particular matter samples were analyzed for organic and elemental carbon (OC and EC), water soluble ions, polycyclic hydrocarbons (PAH), and morphological characteristics. In addition, gas samples during sugarcane biomass burnings were collected and analyzed for volatile organic compounds (VOC) using gas chromatography-mass spectroscopy. Results showed that burning of sugarcane biomass residues (GB and SB) released higher PM_2.5 than RH and CH processes. Carbonaceous compounds contributed the major portions of the fine particles. Ammonium was the major water soluble cation in all particulates and was highly correlated with SO₄^2- concentration. Particulates from sugarcane residue burnings were dominated by low molecular weight PAHs, and GB operation released significantly higher PAHs than SB and CH processes. In addition, analysis of smoke gas samples collected during burning events showed that isoprene and propylene were the major VOCs, and higher numbers of VOCs were released from the GB operation than SB operation. Generally higher molar ratios of CH₄/CO₂ were observed in GB samples as compared to SB, suggesting a more reduced condition under grand burning than standing burning of sugarcane residues.