Sources and risk assessment of atmospheric Hg during the 2022 Beijing Olympic Winter Games

Abstract

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, NO2, and SO2) 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.