Chemical and light absorption properties of humic-like substances from biomass burning emissions under controlled combustion experiments

摘要: Abstract PM2.5 samples from biomass burning (BB) emissions of three types - rice straw (RS), pine needles (PN), and sesame stems (SS) were collected through laboratory-controlled combustion experiments analyzed for the mass, organic elemental carbon (OC EC), water-soluble (WSOC), humic-like substances (HULIS), water soluble inorganic species (Na+, NH4+, K+, Ca2+, Mg2+, Cl−, NO3−, SO42−, oxalate). The carried out at smoldering conditions. Water-soluble HULIS in BB was isolated using a one-step solid phase extraction method, followed by quantification with total analyzer. This study aims to explore chemical light absorption characteristics emissions. contributions (=1.94 × HULIS-C) observed be 29.5 ± 2.0, 15.3 ± 3.1, 25.8 ± 4.0%, respectively, RS, PN, SS smoke samples. Contributions HULIS-C OC WSOC 0.26 ± 0.03 0.63 ± 0.05, 0.15 ± 0.04 0.36 ± 0.08, 0.29 ± 0.08 0.51 ± 0.08, respectively. Light extracts aerosols exhibited strong wavelength dependence, which is characteristic brown spectra sharply increasing as decreases. average Angstrom exponents (AAE) (WSOC) fitted between wavelengths 300–400 nm 8.3 (7.4–9.0), 7.4 (6.2–8.5), 8.0 (7.1–9.3) samples, are comparable AAE values reported previous publications (e.g., field laboratory chamber studies). mass efficiencies measured 365 nm (MAE365) 1.37 ± 0.23, 0.86 ± 0.09, 1.38 ± 0.21 m2/g⋅C aerosols, Correlations WSOC, hydrophilic (= WSOC–HULIS-C), concentrations solution indicate that strongly associated (R2 = 0.92) i.e., hydrophobic component rather than (R2 = 0.31).