Fig. 1: Sulfate formation via Mn-catalytic reaction in chamber experiments.
a Mass concentration and mean diameter growth of NaCl and (NH4)2SO4 seed particles via the Mn-catalytic reaction at 298 K. In the NaCl experiment (open orange circles), the initial Mn2+ concentration was 49.7 ng m−3, the SO2 mixing ratio was 116 ppbv, and the NH3 mixing ratio was 84 ppbv under 80% relative humidity (RH). For the (NH4)2SO4 experiment, the initial Mn concentration was 450.4 ng m−3 (solid blue circles) or 225.4 ng m−3 (solid green circles), and the SO2 and NH3 mixing ratios were the same as those of the NaCl experiment under 89% RH. The dotted and dashed blue lines depict the particle mass concentrations calculated by the Mn-catalytic aqueous phase reaction with and without considering the ionic strength effect. The initial conditions were the same as those of the solid blue circles. b Dependence of sulfate formation rate (r) on Mn (excluding impacts of SO2 mixing ratios and surface area concentration (A), open red circles) and SO2 mixing ratios (excluding impacts of Mn concentration and surface area concentration, open blue circles). Error bars represent standard deviation. c TEM and mapping images of particles collected from the chamber experiments.
