Photochemical reaction of CO2 on atmospheric mineral dusts

Abstract:

The airborne mineral dust has been one of the biggest contributors for atmospheric particulate matter. Currently, average annual emissions for airborne mineral dust are about 1000-3000 Tg·yr^-1. Complex chemistry of mineral dust surfaces might give rise to the conversion of some important atmospheric trace gases. Herein, for the first time we find that CO₂ can be photochemically reduced to CO on mineral dust particles, which is an ozone precursor in the atmosphere. We provide evidence for a pathway in which CO₂ interacts with mineral dust and is converted into CO under artificial solar light. TiO₂ present in mineral dust particles act as photocatalysts promoting the formation of photoinduced electrons, which initiate the photoreduction of CO₂ to CO on the surface of mineral dust. Due to the abundance of CO₂ and mineral dust in the lower atmosphere, this process could cause significant impact on atmosphere and climate. The laboratory findings are supported by recent field observations near Shanghai, China.