Heterogeneous atmospheric chemistry of metal-containing anthropogenic dusts – fly ash to engineered nanomaterials

With the intensification of human activity, aerosols are estimated to have increased by 10-40% since the preindustrial era. Human activities such as biomass burning and incomplete combustion of fossil fuels create an enormous continuous input of particulate matter into the atmosphere with an estimation of 270 Tg Year-1. Fly ash which originates from coal combustion and other industrial sources is one of the typical metal-containing anthropogenic aerosols. Even equipped with highly efficient gas cleaning devices, a considerable concentration of finely sized fraction of fly ash may escape from the combustion stack into the atmosphere with the exhaust gas, resulting in air pollution on both local and regional scales. In addition, the expanding use of engineered nanomaterials has the potential to lead to an increase in the emissions of metal and metal oxide nanoparticles into the environment. Due to their unique properties, metal and metal oxide nanoparticles have to potential to be especially toxic and damaging to the environmental, represent another poorly understood anthropogenic aerosol source. Furthermore, once released into the atmosphere, those anthropogenic dusts can have significant effects on atmospheric chemistry, climate forcing, and human health, as well as biogeochemical cycles. For example, the transport and deposition of naturally-occurring mineral dust has been consider as the major source of solution iron in regions referred to as high nutrient low chlorophyll regions. However, recent evidence from field, modeling and laboratory studies suggested that anthropogenic aerosols from combustion source may play a more important role in providing Fe(II) to these remote regions due to enhanced solubility versus naturally occurring mineral dusts. These studies are fairly recent, but a great deal remains to be regarding the climate properties, heterogeneous atmospheric processing, and eventual deposition/dissolution of anthropogenic dusts. In our laboratory, simulated atmospheric processing experiments were carried out to better understand the effect of heterogeneous atmospheric chemistry in modifying the chemical composition and morphology of the anthropogenic dusts, as well as in iron mobilization from anthropogenic dust. Field collection and characterization of mineral versus anthropogenic dust particles from urban settings have also been incorporated with laboratory studies to better understand the atmospheric processing of anthropogenic aerosols and their subsequent impacts on biogeochemical cycles, human health, and climate