Potential sources, scavenging processes, and source regions of mercury in the wet deposition of South Korea

Sangwoo Eom; Haebum Lee; Jihee Kim; Kihong Park; Younghee Kim; Guey-Rong Sheu; David A Gay; David Schmeltz; Seunghee Han

doi:10.1016/j.scitotenv.2020.143934

Potential sources, scavenging processes, and source regions of mercury in the wet deposition of South Korea

Sci Total Environ. 2021 Mar 25:762:143934. doi: 10.1016/j.scitotenv.2020.143934. Epub 2020 Dec 5.

Authors

Sangwoo Eom¹, Haebum Lee¹, Jihee Kim¹, Kihong Park¹, Younghee Kim², Guey-Rong Sheu³, David A Gay⁴, David Schmeltz⁵, Seunghee Han⁶

Affiliations

¹ School of Earth Sciences and Environmental Engineering, Gwangju Institute of Science and Technology (GIST), Gwangju 61005, Republic of Korea.
² National Institute of Environmental Research (NIER), Incheon 22689, Republic of Korea.
³ Department of Atmospheric Sciences, National Central University, Jhongli 320, Taiwan.
⁴ National Atmospheric Deposition Program, Wisconsin State Laboratory of Hygiene, University of Wisconsin-Madison, Madison, WI 53718, USA.
⁵ Office of Atmospheric Programs, Environmental Protection Agency, Washington, DC, USA.
⁶ School of Earth Sciences and Environmental Engineering, Gwangju Institute of Science and Technology (GIST), Gwangju 61005, Republic of Korea. Electronic address: shan@gist.ac.kr.

Abstract

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^-1) and Seoul (22.5 ng L^-1) than in Jeju (4.0 ng L^-1) and Gwangju (4.1 ng L^-1). The variations in the Hg concentrations in wet deposition of Jeju and Gwangju were related to Cl^-, Na⁺, Mg²⁺, and K⁺ originating from marine and crustal sources, and those in Incheon and Seoul were related to SO₄^2-, NO₃^-, and NH₄⁺ 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.

Keywords: Asian dust; Backward trajectory model; Mercury; Methylmercury; Source; Wet deposition.

Grants and funding

EPA999999/ImEPA/Intramural EPA/United States