Airborne Soil Organic Particles

Atmospheric particles often include heterogeneous internal mixtures of inorganic and organic components within the same individual particles, which contentiously evolve in the atmosphere as a result of their multi-phase chemistry. This presentation will give an overview of recent field and laboratory studies of atmospheric particles where novel complementary methods of chemical imaging and molecular characterization were used by the presenter and his colleagues with an overall goal to understand chemistry of particle components, chemical transformations of particles during atmospheric aging, their environmental and climate impacts.

Until recently, it was believed that the primary processes for aerosolizing soils and entraining soil organic matter (SOM) constituents into the Earth’s atmosphere were natural wind erosion and human mechanical activities such as agricultural tilling or harvesting. However, recent observations at the DOE ARM site in the Southern Great Plains, Oklahoma, USA provided evidence of a previously unrecognized mechanism of atmosphere-land-surface interactions that result in ejection of submicron airborne soil organic particles (ASOP) after intensive precipitation events such as rainfall or irrigation. Chemical imaging and microanalysis of ASOP indicated that they appear as unusual spherical glassy organic solids composed of soil organic matter (SOM). This previously unrecognized type of organic aerosol may have significant impacts on the atmospheric environment in areas where soils are exposed to strong, episodic precipitation events such as agricultural areas or natural grasslands.