Spatial and temporal distribution, species, and potential source analysis of atmospheric particulate mercury in the Yellow and Bohai seas

Abstract

The distribution characteristics of total particulate mercury (TPM), as well as the species of mercury in particulate matter in the winter and summer in the Yellow and Bohai Seas (YBS), were not well understood. Total suspended particulate matter (TSP) samples were collected to determine the concentration level, species characteristics, and potential sources of TPM in the YBS. The annual average TPM concentration in the YBS was 40.4 ± 30.1 pg/m³, and the seasonal variation of TPM followed the order of spring (63.3 ± 26.8 pg/m³), winter (49.6 ± 21.8 pg/m³) and summer (12.7 ± 11.3 pg/m³). The average TPM concentration of the Bohai Sea and the North Yellow Sea (NYS) was higher than that in the South Yellow Sea (SYS). The average concentrations of volatile particulate mercury (VPM) and reactive particulate mercury (RPM) were 0.07 pg/m³ and 0.40 pg/m³, respectively. RPM/TPM exhibited the highest levels in the SYS during the winter and summer seasons. Polluted air masses from northern China in winter, southern China (such as Jiangsu and Zhejiang regions) in spring, eastern coastal provinces of China, and parts of Japan and South Korea in summer were identified as significant sources of TPM in the YBS. Coal combustion accounted for 77.4% of the total TPM emissions, which was the main source of TPM in the YBS. Secondary aerosol played an important role in the transformation of particulate mercury species. The total annual dry deposition of TPM in the YBS was estimated to be 11.6 t/yr, highlighting the significant role of dry deposition as a source of mercury in the YBS.