Comparison of atmospheric PM2.5-bounded mercury species and their correlation with bromine and iodine at coastal urban and island sites in the eastern China

• PM2.5-bounded mercury species were studied at coastal urban and island sites.
• The mass content of PBM was higher at coastal-island than that at coastal-urban.
• Halogen showed different correlations with atmospheric mercury at two sites.

A year-long observation of PM2.5-bounded mercury (PBM) and its species was conducted at a urban site (Shanghai, Xuhui; XH) and an island site (Shengsi, SS) in eastern China from September 2014 to August 2015. The seasonal variation of mercury species including hydrochloric soluble particle-phase mercury (HPM), element soluble particle-phase mercury (EPM) and residual soluble particle-phase mercury (RPM), as well as particulate halogen (Br, I) were determined. Annual average concentration of PBM at urban was 0.32 ± 0.13 ng·m− 3, and was 0.22 ± 0.18 ng·m− 3 at island, which might be attributed to anthropogenic sources. Include more results here, such as EPM, RPM, and with comparison like “The speciated mercury in PM2.5 was found to be HPM > RPM > EPM at the urban site, while RPM > HPM > EPM at island site, respectively.” The speciated mercury in PM2.5 showed distinct different concentrations between the two sites. HPM concentration is the highest at urban, but RPM showed the largest fraction at island. Higher mass contents of all PM2.5-bounded mercury species were found at island site than those at urban site, which indicated atmospheric mercury is more easily scavenged by particles at ocean atmosphere. Additionally, the correlation between bromine and mercury was stronger at urban site than that at island site, while iodine had the stronger correlation with mercury at island site than that urban site. These results showed marine aerosols played an important role to the transport of mercury.