title: Air-sea exchange of gaseous mercury in the East China Sea.
abstract: Two oceanographic cruises were carried out in the East China Sea (ECS) during the summer and fall of 2013. The main objectives of this study are to identify the spatial-temporal distributions of gaseous elemental mercury (GEM) in air and dissolved gaseous mercury (DGM) in surface seawater, and then to estimate the Hg(0) flux. The GEM concentration was lower in summer (1.61 ± 0.32 ng m(-3)) than in fall (2.20 ± 0.58 ng m(-3)). The back-trajectory analysis revealed that the air masses with high GEM levels during fall largely originated from the land, while the air masses with low GEM levels during summer primarily originated from ocean. The spatial distribution patterns of total Hg (THg), fluorescence, and turbidity were consistent with the pattern of DGM with high levels in the nearshore area and low levels in the open sea. Additionally, the levels of percentage of DGM to THg (%DGM) were higher in the open sea than in the nearshore area, which was consistent with the previous studies. The THg concentration in fall was higher (1.47 ± 0.51 ng l(-1)) than those of other open oceans. The DGM concentration (60.1 ± 17.6 pg l(-1)) and Hg(0) flux (4.6 ± 3.6 ng m(-2) h(-1)) in summer were higher than those in fall (DGM: 49.6 ± 12.5 pg l(-1) and Hg(0) flux: 3.6 ± 2.8 ng m(-2) h(-1)). The emission flux of Hg(0) from the ECS was estimated to be 27.6 tons yr(-1), accounting for ∼0.98% of the global Hg oceanic evasion though the ECS only accounts for ∼0.21% of global ocean area, indicating that the ECS plays an important role in the oceanic Hg cycle.
authors.affiliation: Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, No. 18 Shuangqing Road, Beijing 100085, China; Graduate School of Chinese Academy of Sciences, Beijing 100049, China.
authors.forename: Chunjie
authors.initials: C
authors.lastname: Wang
authors.affiliation: Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, No. 18 Shuangqing Road, Beijing 100085, China. Electronic address: zjci@rcees.ac.cn.
authors.forename: Zhijia
authors.initials: Z
authors.lastname: Ci
authors.affiliation: Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, No. 18 Shuangqing Road, Beijing 100085, China.
authors.forename: Zhangwei
authors.initials: Z
authors.lastname: Wang
authors.affiliation: Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, No. 18 Shuangqing Road, Beijing 100085, China.
authors.forename: Xiaoshan
authors.initials: X
authors.lastname: Zhang
mesh_terms: D000393:Air Pollutants / Q000737:chemistry*; D002681:China; D004784:Environmental Monitoring; D004785:Environmental Pollutants / Q000737:chemistry; D005453:Fluorescence; D005740:Gases / Q000737:chemistry*; D008628:Mercury / Q000737:chemistry*; D009792:Oceans and Seas; D012621:Seasons; D012623:Seawater / Q000737:chemistry*
chemical_list: D000393:Air Pollutants; D004785:Environmental Pollutants; D005740:Gases; D008628:Mercury
keywords: Air-sea exchange; Dissolved gaseous mercury; East China Sea; Gaseous elemental mercury