Temporal variation of speciated atmospheric Hg and characteristics of size-fractioned HgP at a suburban site in Shijiazhuang City, North China

Atmospheric mercury (Hg) species were determined at a suburban site near Shijiazhuang, China from May 2016 to January 2017 to ascertain their seasonal and diurnal patterns, to identify the relationship with other parameters, and furthermore to elucidate their potential sources areas. The gaseous elemental Hg (GEM) concentration (3.66 +/- 2.62 ng m(-3)) was about 2 times higher than the background level in the Northern Hemisphere, and the fine particulate bound Hg (Hg-2.5(p)) concentration (92.4 +/- 59.6 pg m(-3)) was comparable to those at urban sites, while the gaseous oxidized Hg (GOM) level was quite low (5.7 +/- 5.6 pg m(-3)). GEM and Hg-2.5(p) concentrations exhibit pronounced seasonal (January > May > October > August) and diurnal (nighttime > daytime) patterns. In contrast, the seasonal and diurnal patterns of GOM were just opposite to those of GEM and Hg-2.5(p). The significant positive relationship among GEM, Hg-P, CO, SO2, and NO2 reveals that they have similar anthropogenic sources. Interestingly, the size distributions of Hg P in PM10 were observed to be unimodal during the four study periods, and peaks were all located in the fine mode (0.7-2.1 mu m), and fine Hg P contributed -70% (38.2-81.5%) of Hg-10(P), indicating that the fine mode was the dominant size. The potential source contribution function (PSCF) result suggests that GEM level at the sampling site was highly impacted by regional sources rather than the long-range transport, and the potential source areas were predominantly located in southern Hebei and western Shandong. The results of wind rose and cluster analyses were consistent with the PSCF results.

Automated summary

This study investigated atmospheric mercury species at a suburban site near Shijiazhuang, China, and found that the concentrations of gaseous elemental mercury and fine particulate bound mercury exhibited pronounced seasonal and diurnal patterns. The mercury pollution in the area was mainly influenced by regional sources, with different forms of mercury being impacted by different sources.