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Atmospheric mercury was measured at an urban site in Beijing during the 2022 Beijing Olympic Winter Games (BOWG) to explore their sources and risks. The mean gaseous elemental mercury (GEM) and particulate bound mercury (PBM) concentrations were 2.75 ± 0.99 ng m−3 and 25.4 ± 67.1 pg m−3, respectively. The implementation of control measures was the dominant reason for low GEM during the BOWG. Similar temporal patterns (GEM, CO, NO 2 , and SO 2) and significant strong positive correlations between them reveal that they had common sources. Based on potential source contribution function and cluster analyses, central/southeastern Hebei, Tianjin, and southern Beijing were the dominant source areas. Air masses associated with high GEM during pollution event (>3.1 ng m−3) generally passed over polluted regions at low speeds and heights. Positive matrix factorization analysis reveals that surrounding coal fired and local vehicle emissions contributed approximately 58% and 30% to the sources, respectively. The PBM risk was higher than that of GEM, and children were more sensitive to atmospheric mercury. Mercury exposure is chronic at a low dosage, resulting loss of malaise, appetite, gastrointestinal upset, and weight. Although atmospheric mercury risk exhibits a decline trend over the past two decades and the current risk is generally low, the cumulative effect over decades or more shouldn't be ignored. The current occasionally high risk values warn people to avoid high-pollution periods. [Display omitted] • GEM level was significantly lower during the BOWG (winter) than during other seasons. • Tianjin and Hebei were identified as dominant source areas for high GEM in Beijing. • External coal burning and local vehicle emissions were major atmospheric Hg sources. • Children were more sensitive to atmospheric Hg risk, and it was great two decades ago. • A decline trend was found for winter atmospheric Hg risk, but summer risk was stable. [ABSTRACT FROM AUTHOR]

Gaseous elemental Hg (GEM), particulate bound Hg (PBM), and gaseous oxidized Hg (GOM) were monitored at an urban site in Beijing, China during wet seasons (July–November) of 2021. The mean (± standard deviation) GEM, PBM, and GOM concentrations were 3.45 ± 1.27 ng m−3, 48.2 ± 88.6 pg m−3, and 13.7 ± 55.0 pg m−3, respectively. GEM level was stable (generally 3.0–4.0 ng m−3) and the average concentration was about twice that of the background level in Beijing, while the occasionally very high PBM and GOM concentrations (>1000 pg m−3) suggest pollution events. Moreover, GEM, CO, and NO 2 exhibit a conspicuous similar diurnal trend with lower values during daytime compared to nighttime under the combined influence of anthropogenic emissions and meteorological factors, and the significantly positive relationship between them indicates that they had similar or common sources. However, the diurnal pattern of reactive Hg (i.e., RM = PBM + GOM) was not pronounced. Both cluster and potential source contribution function analyses show that southern Beijing, Tianjin, as well as central and east Hebei provinces were the dominant source regions for elevated GEM at this monitoring site. The dominant reason for the elevated GEM level (generally >3.5 ng m−3) during pollution event is that majority of air masses originated from the southern polluted regions of this sampling site and traveled at low heights, while the long-range transport of upper clean air masses and continuous high traveling heights were attributed to the low GEM level (<2.0 ng m−3) during clean event. Positive matrix factorization results reveal that regional transport of coal fired air pollutants and local vehicle emissions were the dominant contributors to elevated GEM level, while RM mainly originated from local sources. • Anthropogenic emissions have doubled the gaseous elemental Hg level in Beijing. • The diurnal pattern is pronounced for Hg0, but not for atmospheric reactive Hg. • Southern Beijing, Tianjin, and central Hebei were the dominant potential source areas. • Local vehicle emissions and regional coal fired were the dominant sources for Hg0. • Majority of the atmospheric reactive Hg originated from the local sources. [ABSTRACT FROM AUTHOR]

Gaseous elemental Hg (GEM), particulate bound Hg (PBM), and gaseous oxidized Hg (GOM) were monitored at an urban site in Beijing, China during wet seasons (July–November) of 2021. The mean (± standard deviation) GEM, PBM, and GOM concentrations were 3.45 ± 1.27 ng m−3, 48.2 ± 88.6 pg m−3, and 13.7 ± 55.0 pg m−3, respectively. GEM level was stable (generally 3.0–4.0 ng m−3) and the average concentration was about twice that of the background level in Beijing, while the occasionally very high PBM and GOM concentrations (>1000 pg m−3) suggest pollution events. Moreover, GEM, CO, and NO 2 exhibit a conspicuous similar diurnal trend with lower values during daytime compared to nighttime under the combined influence of anthropogenic emissions and meteorological factors, and the significantly positive relationship between them indicates that they had similar or common sources. However, the diurnal pattern of reactive Hg (i.e., RM = PBM + GOM) was not pronounced. Both cluster and potential source contribution function analyses show that southern Beijing, Tianjin, as well as central and east Hebei provinces were the dominant source regions for elevated GEM at this monitoring site. The dominant reason for the elevated GEM level (generally >3.5 ng m−3) during pollution event is that majority of air masses originated from the southern polluted regions of this sampling site and traveled at low heights, while the long-range transport of upper clean air masses and continuous high traveling heights were attributed to the low GEM level (<2.0 ng m−3) during clean event. Positive matrix factorization results reveal that regional transport of coal fired air pollutants and local vehicle emissions were the dominant contributors to elevated GEM level, while RM mainly originated from local sources. • Anthropogenic emissions have doubled the gaseous elemental Hg level in Beijing. • The diurnal pattern is pronounced for Hg0, but not for atmospheric reactive Hg. • Southern Beijing, Tianjin, and central Hebei were the dominant potential source areas. • Local vehicle emissions and regional coal fired were the dominant sources for Hg0. • Majority of the atmospheric reactive Hg originated from the local sources. [ABSTRACT FROM AUTHOR]