School of Earth Sciences and Environmental Engineering, Gwangju Institute of Science and Technology (GIST), Gwangju 61005, Republic of Korea.
National Institute of Environmental Research (NIER), Incheon 22689, Republic of Korea.
Sci Total Environ. 2021 Mar 25;762:143934. doi: 10.1016/j.scitotenv.2020.143934. Epub 2020 Dec 5.
In this study, the potential sources, scavenging processes, and emission regions for Hg in wet deposition were investigated in rural (Jeju), suburban (Gwangju), and urban sites (Incheon and Seoul) of South Korea. The annual volume-weighted mean concentrations of Hg in wet deposition were four to five times higher in Incheon (16.6 ng L) and Seoul (22.5 ng L) than in Jeju (4.0 ng L) and Gwangju (4.1 ng L). The variations in the Hg concentrations in wet deposition of Jeju and Gwangju were related to Cl, Na, Mg, and K originating from marine and crustal sources, and those in Incheon and Seoul were related to SO, NO, and NH emitted from anthropogenic sources. The below-cloud scavenging was considered a major inclusion process of Hg in Jeju and Gwangju, while the within-cloud scavenging was suggested in Incheon and Seoul, based on the results of correlation analysis with Hg and major ions in wet deposition, and meteorological data. The cluster analysis of backward trajectories demonstrated that the Hg concentration in wet deposition was highest in the cluster transported from Hebei and Shandong of China in Gwangju, but in Seoul, the Hg concentrations of each cluster were comparable. This suggests that regional transport is the major source of Hg in the wet deposition of Gwangju while local transport provides substantial amount of Hg in the wet deposition of Seoul. This was further supported by the results of concentration-weighted trajectories: the most probable source region was east China for Gwangju, and the mid-west of South Korea and east China for Seoul. It is noted that the peak methylmercury concentrations were found every spring with simultaneous increases in atmospheric Al, Ca, Mg, and Fe concentrations, indicating a concurrence with Asian dust. The formation process of methylmercury in Asian dust should be confirmed in future studies.
在这项研究中，调查了韩国农村（济州）、郊区（光州）和城市（仁川和首尔）站点湿沉降中汞的潜在来源、清除过程和排放区域。仁川（16.6ng/L）和首尔（22.5ng/L）的湿沉降中汞的年体积加权平均值浓度是济州（4.0ng/L）和光州（4.1ng/L）的四到五倍。济州和光州湿沉降中汞浓度的变化与来自海洋和地壳源的 Cl、Na、Mg 和 K 有关，而仁川和首尔的汞浓度变化与人为源排放的 SO、NO 和 NH 有关。根据湿沉降中 Hg 和主要离子与气象数据的相关分析结果，认为济州和光州的云下清除是 Hg 主要的包含过程，而仁川和首尔则存在云内清除。后向轨迹聚类分析表明，在光州，来自中国河北和山东的轨迹传输的 Hg 浓度最高，但在首尔，每个轨迹的 Hg 浓度相当。这表明，区域传输是光州湿沉降中 Hg 的主要来源，而本地传输为首尔湿沉降中 Hg 的主要来源。浓度加权轨迹的结果进一步支持了这一结论：对于光州，最可能的源区是中国东部，对于首尔，最可能的源区是韩国中西部和中国东部。需要注意的是，每年春天都会出现甲基汞浓度峰值，同时大气中的 Al、Ca、Mg 和 Fe 浓度也会增加，表明与亚洲沙尘有关。未来的研究应该确认亚洲沙尘中甲基汞的形成过程。
