Department of Atmospheric Sciences, National Central University, Jhongli, 320, Taiwan.
Environment and Climate Change Canada, Toronto, Ontario, Canada.
Environ Pollut. 2019 Dec;255(Pt 1):113128. doi: 10.1016/j.envpol.2019.113128. Epub 2019 Aug 30.
Atmospheric deposition, either dry or wet, has been identified as an important pathway of mercury (Hg) input to terrestrial and aquatic systems. Although East Asia is the major atmospheric Hg emission source region, very few studies have been conducted to quantify atmospheric Hg deposition in its downwind region. In this study, 8-year (2009-2016) atmospheric Hg dry deposition was reported at the Lulin Atmospheric Background Station (LABS), a high mountain forest site in central Taiwan. Dry deposition of speciated Hg was estimated using a bi-directional air-surface flux exchange model for gaseous elemental mercury (GEM) and dry deposition models for gaseous oxidized mercury (GOM) and particulate-bound mercury (PBM), making use of the monitored speciated atmospheric Hg concentrations. Annual total Hg dry deposition ranged from 51.9 to 84.9 μg m yr, with a multi-year average of 66.1 μg m yr. Among the three forms of atmospheric Hg, GEM was the main contributor to the total dry deposition, contributing about 77.8% to the total, due to the high density of forest canopy as well as the much higher concentration of GEM than GOM and PBM at LABS. Mercury dry deposition is higher in winter and spring than in summer and fall, partly due to the elevated Hg concentrations associated with air masses from East and Southeast Asia where with high atmospheric Hg emissions. The mean annual dry/wet deposition ratio of 2.8 at LABS indicated that Hg deposition to forest landscape was governed by dry rather than wet deposition.
大气沉降（无论是干沉降还是湿沉降）已被确定为汞（Hg）输入陆地和水生系统的重要途径。尽管东亚是大气 Hg 排放的主要源区，但很少有研究对其下风区的大气 Hg 沉降进行量化。本研究报道了台湾中部高山森林站点鹿林大气背景站（LABS） 8 年（2009-2016 年）大气 Hg 干沉降。利用监测到的大气 Hg 浓度，使用双向气-固通量交换模型估算气态元素汞（GEM）的干沉降，以及气态氧化汞（GOM）和颗粒结合态汞（PBM）的干沉降模型来估算 GEM 的干沉降。年均总 Hg 干沉降量为 51.9-84.9μg m yr，多年平均值为 66.1μg m yr。在三种大气 Hg 形态中，GEM 是总干沉降的主要贡献者，约占总沉降量的 77.8%，这是由于森林树冠密度高，以及 GEM 浓度远高于 GOM 和 PBM。Hg 干沉降在冬季和春季高于夏季和秋季，部分原因是与东亚和东南亚气团有关的 Hg 浓度升高，这些地区大气 Hg 排放量高。LABS 的年均干/湿沉降比为 2.8，表明 Hg 沉积到森林景观主要受干沉降控制，而不是湿沉降。
