Air–sea exchange of gaseous mercury in the tropical coast (Luhuitou fringing reef) of the South China Sea, the Hainan Island, China
Air–sea exchange of gaseous mercury in the tropical coast (Luhuitou fringing reef) of the South China Sea, the Hainan Island, China
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DOI：
10.1007/s11356-016-6346-5
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发表时间：
2016-03
影响因子：
5.8
通讯作者：
Zhijia Ci;Xiaoshan Zhang;Zhangwei Wang
中科院分区：
文献类型：
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作者：
Zhijia Ci;Xiaoshan Zhang;Zhangwei Wang
热带海洋气态汞（主要是Hg（0））的海气交换是全球汞地球化学循环的重要组成部分，但相关研究还很有限。2015年1 - 2月，我们对海南岛南海热带岸礁（鹿回头礁）表层沃茨和上覆大气中Hg（0）浓度进行了连续13天的同步观测。本研究旨在探讨热带海岸带大气和沃茨中Hg（0）浓度的时间变化，估算大气-海洋Hg（0）通量，并揭示其影响因素。空气中Hg（0）和沃茨中总汞（THg）的平均浓度（±SD）分别为2.34 ± 0.26 ng m− 3和1.40 ± 0.48 ng L−1。冬季沃茨中Hg（0）浓度（53.7 ± 18.8 pg L−1）和Hg（0）/THg比值（3.8%）均显著高于南海开放水域。沃茨中Hg（0）的日变化明显，白天浓度升高，夜间浓度降低，尤其是在无云、低风速的天气。线性回归分析表明，沃茨中Hg（0）浓度与光合有效辐射（PAR）呈显著正相关（R2= 0.42，p < 0.001）。与空气相比，地表沃茨中的Hg（0）总是过饱和（饱和度为2.46 - 13.87），表明地表水体是大气Hg（0）的来源之一。大气-海洋Hg（0）通量估计为1.73 ± 1.25 ng m− 2 h − 1，范围在0.01和6.06 ng m− 2 h −1之间。Hg（0）通量的高变化主要归因于风速的大的时间变化。
The air–sea exchange of gaseous mercury (mainly Hg(0)) in the tropical ocean is an important part of the global Hg biogeochemical cycle, but the related investigations are limited. In this study, we simultaneously measured Hg(0) concentrations in surface waters and overlaying air in the tropical coast (Luhuitou fringing reef) of the South China Sea (SCS), Hainan Island, China, for 13 days on January–February 2015. The purpose of this study was to explore the temporal variation of Hg(0) concentrations in air and surface waters, estimate the air–sea Hg(0) flux, and reveal their influencing factors in the tropical coastal environment. The mean concentrations (±SD) of Hg(0) in air and total Hg (THg) in waters were 2.34 ± 0.26 ng m−3and 1.40 ± 0.48 ng L−1, respectively. Both Hg(0) concentrations in waters (53.7 ± 18.8 pg L−1) and Hg(0)/THg ratios (3.8 %) in this study were significantly higher than those of the open water of the SCS in winter. Hg(0) in waters usually exhibited a clear diurnal variation with increased concentrations in daytime and decreased concentrations in nighttime, especially in cloudless days with low wind speed. Linear regression analysis suggested that Hg(0) concentrations in waters were positively and significantly correlated to the photosynthetically active radiation (PAR) (R2= 0.42,p< 0.001). Surface waters were always supersaturated with Hg(0) compared to air (the degree of saturation, 2.46 to 13.87), indicating that the surface water was one of the atmospheric Hg(0) sources. The air–sea Hg(0) fluxes were estimated to be 1.73 ± 1.25 ng m−2h−1with a large range between 0.01 and 6.06 ng m−2h−1. The high variation of Hg(0) fluxes was mainly attributed to the greatly temporal variation of wind speed.