Combustion

Chemistry

Particulates

Ozone

Photochemistry

Transition metal

Chemical physics

Aerosol

Physics

Haze

Geology

Meteorology

Organic chemistry

Atmosphere (unit)

Atmospheric sciences

Catalysis

Sulfate aerosol

Atmospheric chemistry

Environmental chemistry

Coal combustion products

Sulfur

Inorganic chemistry

Sulfate

Environmental science

Physical chemistry

Manganese

Nature Communications

The formation mechanism of aerosol sulfate during wintertime haze events in China is still largely unknown. As companions, SO 2 and transition metals are mainly emitted from coal combustion. Here, we argue that the transition metal-catalyzed oxidation of SO 2 on aerosol surfaces could be the dominant sulfate formation pathway and investigate this hypothesis by integrating chamber experiments, numerical simulations and in-field observations. Our analysis shows that the contribution of the manganese-catalyzed oxidation of SO 2 on aerosol surfaces is approximately one to two orders of magnitude larger than previously known routes, and contributes 69.2% ± 5.0% of the particulate sulfur production during haze events. This formation pathway could explain the missing source of sulfate and improve the understanding of atmospheric chemistry and climate change.

Sulfate formation is dominated by manganese-catalyzed oxidation of SO2 on aerosol surfaces during haze events