Abstract
Abstract. Total gaseous mercury (TGM) was continuously monitored at a remote site (CBS) in Mt. Changbai area, Northeastern China from 24 October 2008 to 31 October 2010. The overall mean TGM concentration was 1.60±0.51 ng m−3, which is lower than those reported from remote sites in Eastern, Southwestern, and Western China, indicating a relatively lower regional anthropogenic mercury (Hg) emission intensity in Northeastern China. Measurements at a site in the vicinity (~1.2 km) of CBS station from August 2005 to July 2006 showed a significantly higher mean TGM concentration of 3.58±1.78 ng m−3. The divergent result was partially attributed to fluctuations in the relatively frequencies of surface winds during the two study periods and moreover an effect of local emission sources. The temporal variation of TGM at CBS was influenced by regional sources as well as long-range transported Hg. Regional sources frequently contributing to episodical high TGM concentrations were pin-pointed as a large iron mining district in Northern North Korea and two large power plants and urban areas to the southwest of the sampling site. Source areas in Beijing, Tianjin, southern Liaoning, Hebei, northwestern Shanxi, and northwestern Shandong were found to contribute to elevated TGM observations at CBS via long-range transport. Diurnal pattern of TGM at CBS was mainly controlled by regional sources, likely as well as intrusion of air masses from the free troposphere during summer season. There are no consistent seasonal pattern of TGM at CBS, and the monthly TGM variations showed links with the patterns of regional air movements and long-range transport.
Highlights
Mercury (Hg) is a persistent, bio-accumulative and toxic chemical in the environment and has potential adverse effects on human health
Hg in the atmosphere, which is derived from both anthropogenic and natural emission sources, is generally operationally defined into three major forms, namely elemental gaseous mercury (GEM), gaseous oxidized mercury (GOM), and particulate bounded mercury (PBM), with the sum of GEM and GOM known as total gaseous mercury (TGM)
Long-term continuous measurements of TGM concentrations from the Canadian Atmospheric Mercury Measurement Network (CAMNet) showed that mean TGM concentrations were in the range of 1.36–1.78 ng m−3 (Temme et al, 2007)
Summary
Mercury (Hg) is a persistent, bio-accumulative and toxic chemical in the environment and has potential adverse effects on human health. A study conducted in a remote region of Southwestern China showed a mean TGM concentration of 2.80±1.51 ng m−3 (Fu et al, 2010), which is highly elevated compared to the northern hemispherical background (1.5∼1.7 ng m−3, Lindberg et al, 2007; Valente et al, 2007). We conducted two years of continuous measurements of atmospheric TGM at a remote site in Mt. Changbai area, Northeastern China. Based on this long-term data set, we discuss in this paper the impacts of local and regional sources on the observations. We have used a hybrid receptor model to identify the potential source regions and pathways that contributing to the elevated TGM concentrations in the study area via long-range transport
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