Collaborative Research: Interwoven biogeochemical cycles and biological transformations of mercury and selenium in the upper ocean

来自康涅狄格大学、伍兹霍尔海洋研究所和哈佛大学的研究人员计划解决与全球生物地球化学汞（Hg）和硒（Se）循环相关的三个问题，即：(1)甲基化汞和硒化合物在海洋上层形成的非生物和生物机制是什么？(2)光化学反应在汞、硒海气交换中的作用是什么？(3)汞和硒的生物地球化学循环关系如何？为了实现他们的目标，科学家们将参加一次前往热带北太平洋的机会巡航，并进行实验室培养和对照孵化实验。在巡航期间收集的样本将用于确定汞和硒的形态，以及光化学状态（即紫外线、臭氧、光照水平）、化学（即天然有机物、氧化还原金属）和生物（即叶绿素a、浮游植物组成、蛋白质组学、碳矿化估计）特性的测量。实验室培养和受控孵育实验将用于确定汞和硒化合物形成和降解的特定途径，特别是光化学转化的作用，以及评估硒作为海洋环境中汞的结合配体的重要性。最后，研究人员将继续发展GEOS-Chem全球生物化学汞模型的海洋子模型，以包括硒的循环，并将使用该模型来确定这两个元素的各种转换和逃避过程在全球循环中的重要性。至于更广泛的影响，这项研究具有社会效益，因为它将提高我们对汞如何进入影响人类健康的海鲜的理解。研究结果将列入课程材料。康涅狄格大学的一名研究生、哈佛大学的一名博士后和伍兹霍尔海洋研究所的一名研究生将作为该项目的一部分得到支持和培训。

Researchers from the University of Connecticut, Woods Hole Oceanographic Institution, and Harvard University plan to address three questions related to the global biogeochemical mercury (Hg) and selenium (Se) cycles, namely (1) what are the abiotic and biotic mechanisms for formation of methylated Hg and Se compounds in the upper ocean?; (2) what is the role of photochemical reactions in air-sea exchange of Hg and Se?; and (3) how are the biogeochemical cycles of Hg and Se related? To attain their goal, the scientists will participate in a cruise of opportunity to the Tropical North Pacific, as well as carry out laboratory culture and controlled incubation experiments. Samples collected during the cruise will be used to determine the speciation of Hg and Se, as well as obtain measurements of photochemical status (i.e., UV, ozone, light levels, chemical (i.e., natural organic matter, redox metals), and biological (i.e., chlorophyll a, phytoplankton composition,proteomics, estimates of carbon mineralization) properties. The laboratory culture and controlled incubation experiments will be used to determine the specific pathways for Hg and Se compound formation and degradation, especially the role of photochemical transformations, as well as assess the importance of Se as a binding ligand for Hg in the marine environment. Lastly, the researchers will continue to develop the oceanic sub-model of the GEOS-Chem global biochemical Hg model to include the cycling of Se and will use the model to ascertain the importance of various processes of conversion and evasion in the global cycles of these two elements. As regards broader impacts, this study has societal benefits because it would improve our understanding on how mercury enters seafood which impacts human health. Results from the research would be included in curriculum material. One graduate student from the University of Connecticut, one postdoc from Harvard University, and one graduate student from Woods Hole Oceanographic Institution would be supported and trained as part of the project.