Distribution Characteristics and Source Analysis of Atmospheric Mercury Speciation in Suzhou

Abstract

To explore the variation of mercury in the atmosphere in Suzhou, continuous monitoring of gaseous element mercury (GEM), gaseous oxidized mercury (GOM), and particulate bound mercury (PBM) was conducted from January 1 to December 31, 2018, in Suzhou. The weights trajectory analysis method (CWT) and concentration rose were used to analyze the atmospheric mercury sources and concentration variation. The results showed that during the monitoring period, the concentration ranges of GEM, GOM, and PBM in Suzhou were 0-53.3 ng·m-3, 0-256 pg·m-3, and 0-5208 pg·m-3, respectively. The corresponding annual average concentrations of the three mercury species were (2.57±2.09) ng·m-3, (5.27±15.7) pg·m-3, and (16.0±157) pg·m-3, respectively. GEM was the main component of atmospheric mercury in Suzhou. During the monitoring period, the average concentration of GEM in Suzhou was highest in winter, higher in spring than in autumn, and lowest in summer. According to the CWT, the mercury-containing air mass in spring and winter predominantly originated from inland; in summer, it mainly originated from the local area, the Yellow Sea, and the East China Sea, and in autumn from inland, the Yellow Sea, and the Bohai Sea. The wind and mercury rose charts showed that atmospheric mercury concentrations were higher from inland and lower from the ocean. During the monitoring period, the average concentrations of GEM and PBM in Suzhou were lower during the day than the night. The diurnal variation of GEM and PBM was significantly and strongly correlated with solar radiation, humidity, and air temperature. The average concentration of GOM showed multiple peaks and valleys in one day. Some peaks were caused by fuel oil combustion emissions, and some by O3 oxidation with GEM.