Collaborative research: Transformations and mercury isotopic fractionation of methylmercury by marine phytoplankton

合作研究：海洋浮游植物对甲基汞的转化和汞同位素分馏

• 批准号: 1634024
• 负责人: Nicholas Fisher
• 金额: $ 36.18万
• 依托单位: SUNY at Stony Brook
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-09-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1634024&HistoricalAwards=false
• 关键词: Collaborative; research; Transformations; mercury; isotopic

The accumulation of mercury (Hg) in seafood is a public health concern. The presence of Hg in seafood depends to a large degree on the air-sea exchange of Hg, with atmospheric deposition leading to accumulation of Hg in the ocean. The pathways to seafood start with the uptake of Hg by phytoplankton from seawater where is has always been assumed to accumulate to be eaten by grazers and passed on to larger organisms. This project challenges this assumption with preliminary data that suggests certain phytoplankton species can transform Hg to volatile forms (mercury vapor & dimethylmercury) that are lost to the atmosphere, a processes that removes Hg from the ocean rather than simply concentrating it into the ecosystem and seafood. This process, which has not been studied before, could dramatically alter our view of the Hg cycle in the ocean. The researchers funded by this project will look for the specific phytoplankton species that are capable of volatilizing Hg and quantify the rates at which they do so. They will also examine the suspected role of associated sulfur and selenium compounds in the process, as well as quantifying the changes in the Hg isotopic values for potential use as chemical tracers of the source of Hg in the ecosystem and food supply. These results should allow oceanographers to better quantify and refine our knowledge of Hg cycling in the ocean. The project will support participation of graduate students, a postdoctoral scientist, and incorporation of new information directly into courses taught by the researchers. Funding will also support continuing activities by the participants in activities that disseminate information on mercury and its effect on public and environmental health. Biogeochemical cycling of mercury (Hg) in the ocean may be more complex than previously assumed. New evidence has challenged the idea that methylmercury (MeHg) merely accumulates in phytoplankton and undergoes little to no transformation before being passed into the food web. This project aims to more fully elucidate the mechanisms behind the intracellular transformation of MeHg to volatile Hg and dimethylmercury (Me2Hg) that can be lost to the atmosphere, as well as to evaluate the range of algal taxa that can perform this transformation using directed culture work. Additionally, the PIs will investigate evidence that thiols, organic selenium (Se) compounds, and sulfides are required to facilitate these reactions within the phytoplankton, and specific pathways will be investigated and quantified through this research. Stable Hg isotopic data has been used to track Hg sources and pathways in marine systems and its fractionation during these MeHg transformations will also be quantified for future field study of marine Hg. The investigators hypothesize that coccolithophorids and other haptophytes capable of these intracellular reactions may account for a significant portion of the production of volatile Hg in the ocean. If this turns out to be the case, understanding and quantifying these volatilization processes may significantly alter our current understanding of the overall biogeochemical cycling of Hg in the ocean.

海产品中汞的积累是一个公共卫生问题。 海产品中汞的存在在很大程度上取决于汞的海气交换，大气沉降导致汞在海洋中积累。海产品的生成途径始于浮游植物从海水中吸收汞，人们一直认为海水中的汞会积累起来，被食草动物吃掉，然后传给更大的生物。该项目对这一假设提出了挑战，初步数据表明，某些浮游植物物种可以将汞转化为挥发性形式（汞蒸气和二甲基汞），然后消失在大气中，这一过程将汞从海洋中去除，而不是简单地将其集中在生态系统和海产品中。这一过程以前从未被研究过，可能会极大地改变我们对海洋中汞循环的看法。该项目资助的研究人员将寻找能够挥发汞的特定浮游植物种类，并量化它们挥发汞的速率。 他们还将研究相关的硫和硒化合物在这一过程中可能发挥的作用，并量化汞同位素值的变化，以作为生态系统和食物供应中汞来源的化学示踪剂。这些结果将使海洋学家能够更好地量化和完善我们对海洋中汞循环的知识。该项目将支持研究生、博士后科学家的参与，并将新信息直接纳入研究人员教授的课程。供资还将支持参与者继续开展活动，传播有关汞及其对公众和环境健康影响的信息。海洋中汞（Hg）的生物地球化学循环可能比以前设想的更为复杂。新的证据挑战了甲基汞（MeHg）仅在浮游植物中积累的想法，并且在进入食物网之前几乎没有转化。该项目旨在更全面地阐明甲基汞在细胞内转化为挥发性汞和二甲基汞（Me2Hg）的机制，这些汞可能会流失到大气中，并评估能够利用定向培养工作进行这种转化的藻类类群的范围。此外，PI将调查硫醇，有机硒（Se）化合物和硫化物需要促进浮游植物内的这些反应的证据，并通过这项研究调查和量化特定的途径。稳定的汞同位素数据已被用来跟踪汞的来源和途径，在海洋系统和分馏过程中，这些甲基汞的转换也将被量化为未来的海洋汞的实地研究。研究人员推测，球石藻和其他能够进行这些细胞内反应的附着植物可能是海洋中挥发性汞产生的重要原因。如果事实证明是这样的话，了解和量化这些挥发过程可能会大大改变我们目前对海洋中汞的整体地球化学循环的理解。

项目成果

Bioaccumulation of methylmercury in a marine diatom and the influence of dissolved organic matter.

甲基汞在海洋硅藻中的生物累积以及溶解有机物的影响。

• DOI: 10.1016/j.marchem.2017.09.005
• 发表时间: 2017
• 期刊: Marine chemistry
• 影响因子: 3
• 作者: Lee,Cheng-Shiuan;Fisher,NicholasS
• 通讯作者: Fisher,NicholasS

Mercury Stable Isotopes Reveal Influence of Foraging Depth on Mercury Concentrations and Growth in Pacific Bluefin Tuna

• DOI: 10.1021/acs.est.7b06429
• 发表时间: 2018-06-05
• 期刊: ENVIRONMENTAL SCIENCE & TECHNOLOGY
• 影响因子: 11.4
• 作者: Madigan, Daniel J.;Li, Miling;Sunderland, Elsie M.
• 通讯作者: Sunderland, Elsie M.

Trophodynamics and mercury bioaccumulation in reef and open-ocean fishes from The Bahamas with a focus on two teleost predators.

巴哈马珊瑚礁和公海鱼类的营养动力学和汞生物累积，重点关注两种硬骨鱼捕食者。

• DOI: 10.3354/meps12798
• 发表时间: 2019
• 期刊: Marine ecology progress series
• 影响因子: 2.5
• 作者: Shipley,OliverN;Lee,Cheng-Shiuan;Fisher,NicholasS;Burruss,Georgiana;Frisk,MichaelG;Brooks,EdwardJ;Zuckerman,ZacharyC;Herrmann,AchimD;Madigan,DanielJ
• 通讯作者: Madigan,DanielJ

Microbial generation of elemental mercury from dissolved methylmercury in seawater.

微生物从海水中溶解的甲基汞产生元素汞。

• DOI: 10.1002/lno.11068
• 发表时间: 2019
• 期刊: Limnology and oceanography
• 影响因子: 4.5
• 作者: Lee,Cheng-Shiuan;Fisher,NicholasS
• 通讯作者: Fisher,NicholasS

Declining Mercury Concentrations in Bluefin Tuna Reflect Reduced Emissions to the North Atlantic Ocean.

• DOI: 10.1021/acs.est.6b04328
• 发表时间: 2016-12-06
• 期刊: ENVIRONMENTAL SCIENCE & TECHNOLOGY
• 影响因子: 11.4
• 作者: Lee, Cheng-Shiuan;Lutcayage, Molly E.;Chandler, Emily;Madigan, Daniel J.;Cerrato, Robert M.;Fisher, Nicholas S.
• 通讯作者: Fisher, Nicholas S.