Direct emissions of particulate glyoxal and methylglyoxal from biomass burning and coal combustion

Glyoxal (Gly) and methylglyoxal (Mgly) are key precursors globally for secondary organic aerosol (SOA) formation. These two species were often thought to be formed in the atmosphere via photochemical oxidation of organics from biogenic and anthropogenic origins, although few studies have shown their direct emissions. In this study, we report direct emissions of particulate Gly and Mgly from different residential fuels typically used in north China. The emission ratios (ERs) and emission factors (EFs) of particulate Gly and Mgly for biomass burning were approximate 5-fold and 7-fold higher than those for coal combustion, respectively. The large variances in emissions of Gly and Mgly could be attributed to the different combustion processes, which influenced by the fuel types and combustion conditions. The averaged ERs and EFs of particulate Gly and Mgly were about one order of magnitude lower than their gaseous counterparts due to the low Henry's law constant, which was also consistent with the low particle-to-gas ratio of Gly (0.04) and Mgly (0.02). Our results suggest that the direct emissions of Gly and Mgly from emission sources should be considered when estimating the formation of SOA from Gly and Mgly.

Automated summary

In this study, direct emissions of particulate Gly and Mgly from different residential fuels used in north China were reported. The emission ratios and emission factors of particulate Gly and Mgly for biomass burning were higher than those for coal combustion. The difference in emissions could be attributed to the different combustion processes influenced by fuel types and combustion conditions. The results suggest the importance of considering direct emissions from emission sources when estimating the formation of SOA from Gly and Mgly.