Air-Sea Exchange and Boundary Layer Chemistry of Mercury over the Open Ocean

公海上空-海交换和汞的边界层化学

• 批准号: 0728750
• 负责人: William Fitzgerald
• 金额: --
• 依托单位: University of Connecticut
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-09-01 至 2011-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0728750&HistoricalAwards=false
• 关键词: Air; Sea; Exchange; Boundary; Layer

The atmosphere is the most important source of mercury (Hg) to the marine environment and air-sea exchange is a major pathway for both the addition and removal of Hg from the atmosphere. Preliminary data suggests that the cycling of Hg at the air-sea interface is a complex process involving abiotic (photochemical) oxidation of elemental Hg (Hg0) and reduction of ionic Hg (HgII) in surface waters, as well as oxidation of Hg0 in the atmospheric boundary layer. A scientist from the University of Connecticut plans to assess the importance of these processes by determining the variation in the speciation of Hg and other ancillary measurements in atmospheric and surface water samples recovered from one site in the North Atlantic near Bermuda and another from Cape Point, South Africa. The resulting data set would be used to test the following three hypotheses: (1) photochemical oxidation of Hg0 in surface seawater occurs but the overall net reaction is HgII reduction; (2) organic matter is the primary dissolved constituent influencing the rate of HgII reductions in surface seawater; and (3) oxidation of Hg0 in the marine boundary layer and subsequent dry deposition of HgII compounds is substantial and rivals that of wet deposition. Controlled incubation experiments would also be carried out to determine redox transformations in surface waters. Lastly, the data from the project would be used to constrain and improve ocean and global Hg models, as well as incorporate their results into model simulations using the Harvard University GEOS-Chem modeling framework. As regards broader impacts, this study would further our understanding of the Hg cycle. This study would allow U.S. scientists to interact with their counterparts in South Africa and would continue to build international collaborations with South African institutions. One postdoc, one graduate student, and one undergraduate student would be supported and trained as part of this project.

大气是海洋环境中汞的最重要来源，海-气交换是大气中汞的增加和去除的主要途径。 初步数据表明，汞在海-气界面的循环是一个复杂的过程，涉及元素汞（Hg 0）的非生物（光化学）氧化和表面沃茨中离子汞（Hg II）的还原，以及大气边界层中Hg 0的氧化。 康涅狄格大学的一位科学家计划评估这些过程的重要性，方法是确定从北大西洋百慕大附近的一个地点和南非开普角的另一个地点采集的大气和地表水样本中汞的形态变化和其他辅助测量结果。 由此产生的数据集将用于检验以下三个假设：（1）表层海水中Hg 0发生光化学氧化，但总的净反应是HgII还原;（2）有机物是影响表层海水中HgII还原速率的主要溶解成分;（3）Hg 0在海洋边界层中的氧化和HgII化合物的干沉降是显著的，与湿沉降相当。 还将进行受控培养实验，以确定表层沃茨中的氧化还原转化。 最后，该项目的数据将用于约束和改进海洋和全球汞模型，并将其结果纳入利用哈佛大学全球对地观测系统-化学建模框架进行的模型模拟。 至于更广泛的影响，这项研究将进一步加深我们对汞循环的理解。 这项研究将使美国科学家能够与南非的同行互动，并将继续与南非机构建立国际合作。 一名博士后，一名研究生和一名本科生将作为该项目的一部分得到支持和培训。