Aerosol emission from soil during field burning

Soil is heated or burned during field biomass burning, including forest fires, grassland fires, and open straw burning. The characteristics of the aerosols released from the high-temperature heated soil have not been reported, according to our knowledge. In this work, three types of soil were heated at different temperatures in a tubular furnace to mimic the heating process during field burning. The particulate emission factors (EFPM), particle size distributions, organic carbon (OC) contents, and organic compositions of the emitted aerosols were investigated in detail. It was found that the particulate matter (PM) produced by soil at high temperature (≥300 °C) cannot be neglected. The PM emission flux of the shallow surface of soil (with depth less than 5 cm) could be dozens of times higher than those from biomass burning when the surface temperature rises to 500 °C. The soil heated at higher temperatures emitted more particles with smaller sizes. These aerosols also contain toxic and harmful substances such as aromatics, heterocycles and nitriles. Therefore, the results strongly suggest that aerosol emissions from the heated soil during the field biomass burning cannot be ignored and could have significant environmental impacts.