Differences in the transformation and sources of atmospheric particulate mercury forms during haze weather processes...

To reveal the differences in mercury speciation transformation and sources between inland and coastal metropolises under high pollution conditions, this study simultaneously observed the speciation of particulate mercury (PHg) during haze events in Jinan, an inland city in northern China, and Qingdao, a coastal city. The results showed that as the haze intensified, the concentrations of all PHg species increased significantly, and the haze favored the formation of volatile particulate mercury (VPM) and reactive particulate mercury (RPM), increasing their proportions. Secondary aerosol formation during haze events promoted the oxidation of gaseous elemental mercury (GEM) to Hg²⁺ and facilitated the generation of RPM. In the coastal city, rapid oxidation processes dominated by halogen species in marine aerosols may result in a relatively higher proportion of RPM. Backward trajectory analysis indicated that haze pollution in Qingdao was mainly driven by local accumulation and secondary transformation, while in Jinan, it was simultaneously affected by local emissions and regional transport from surrounding areas. This study revealed significant differences in the sources, speciation transformation, and transport characteristics of PHg under haze conditions between inland and coastal cities, providing a scientific basis for formulating the same region-specific strategies for the prevention and control of atmospheric mercury pollution.