MRI: Acquisition of a field-deployable mass spectrometer for biogeochemical research and education.

该奖项将促进质子转移反应质谱仪（PTR-MS）的购买，以研究与水生环境中挥发性硫，氮和碳化合物的生物地球化学循环有关的各种问题。 质谱仪已成为实验室研究中的宝贵工具，大量研究机构拥有质谱核心设施就是明证。 然而，在实地，特别是在海洋考察中，经常使用的质谱仪要少得多。 PTR-MS系统将提供无与伦比的能力，能够同时测量研究船上和偏远野外营地中的二氧化碳、甲烷、一氧化二氮和二甲硫醚等一些具有生态和气候重要性的化合物的浓度和通量参数。 该仪器将为本科生和研究生的研究提供一种新颖的、最先进的研究工具，正在进行的研究指出，人们对涉及浮游植物、二甲基硫醚和云形成的气候反馈机制知之甚少，这反过来又阻碍了成功模拟这些机制的努力。 需要完善海洋二甲基硫系统循环中的许多功能关系，以改进今后的模型，包括发展特定分类群的关系。 同样，目前的模型无法成功和一致地再现周期的某些特征，如“夏季DMS悖论”，这表明某些模型可能没有纳入或准确描述关键过程。 海洋前体二甲基磺基丙酸酯（DMSP）裂解为DMS或脱甲基为其他S-化合物的相对比例也被认为是对DMS生产的重要控制，但控制这些比例的因素仍不清楚。 与此同时，全球气候的变化预计会在世界上引起一系列的物理化学反应？这将对海洋浮游植物群落产生深远的影响，无论是在细胞水平（生理）和群落水平（生态）。 这些影响可能通过营养循环的变化发生，如铁或氮，或控制浮游植物生长的非生物因素的变化，如温度和光照。 根据所涉及的类群，浮游植物群落的反应将对全球生物地球化学循环产生积极和消极的影响，包括碳、氮和硫的循环，以及涉及这些元素的反馈机制。 PTR-MS系统将用于解决硫、氮和碳的生物地球化学循环中的一些关键问题，包括物种特异性细胞内DMSP浓度和生物合成速率、浮游植物代谢组学、维生素B12在DMSP产生中的作用和海洋DMS水平的调节、海水氨浓度以及海洋DMS和氨排放之间的耦合，南极湖泊和冰下环境的地球化学循环。 在这些调查过程中从PTR-MS系统获得的结果将促进对水生生物地球化学过程的理解，并提供关于在细胞和生态系统两个层面上形成（或降解）一些具有重要生物地球化学意义的化合物的速率以及关键生物地球化学途径的相对重要性的关键信息。 这些数据将有助于完善全球地球化学和气候模型。

This award will facilitate the purchase of a Proton Transfer Reaction Mass Spectrometer (PTR-MS) to study a variety of questions relating to the biogeochemical cycling of volatile sulfur, nitrogen and carbon compounds in aquatic environments. Mass spectrometers have become an invaluable tool in the laboratory research, as evidenced by the large number of research institutions with mass spectrometry core facilities. Yet, considerably fewer mass spectrometers are routinely used in the field, particularly on oceanographic expeditions. The PTR-MS system will provide an unparalleled ability to simultaneously measure parameters relating to the concentrations and fluxes of a number of ecologically and climatically important compounds such as carbon dioxide, methane, nitrous oxide and dimethylsulfide (DMS) onboard research ships and in remote field camps. The instrument will provide a novel and state-of-the-art research tool for undergraduate and graduate research.Ongoing studies point out that climate feedback mechanisms involving phytoplankton, DMS and cloud formation are poorly understand, which in turn hinders efforts to successfully model them. Refinement of many of the functional relationships in the oceanic DMS cycle is required to improve future models, including developing taxon-specific relationships. Similarly, the inability of current models to successfully and consistently reproduce some features of the cycle, such as the "summer DMS paradox", suggests that key processes may not be incorporated or accurately depicted in some models. The relative proportions of the cleavage of the oceanic precursor dimethylsulfoniopropionate (DMSP) to DMS or demethylation to other S-compounds are also thought to be an important control on DMS production, but the factors controlling these proportions remain unclear. Concurrently, changing global climate is expected to cause an array of physico-chemical responses in the world?s oceans that will have profound impact on marine phytoplankton communities both at a cellular level (physiologically) and at a community level (ecologically). The impacts could occur through changes in nutrient cycling, such as iron or nitrogen, or changes in abiotic factors that control phytoplankton growth, such as temperature and light. Depending on the taxa involved, the responses of the phytoplankton communities will impact both positively and negatively global biogeochemical cycles, including those of carbon, nitrogen and sulfur, and feedback mechanisms involving those elements. The PTR-MS system will be used to address a number of critical questions in the biogeochemical cycling of sulfur, nitrogen and carbon, including species-specific intracellular DMSP concentrations and biosynthesis rates, phytoplankton metabolomics, the role of vitamin B12 in the production of DMSP and the modulation of oceanic DMS levels, seawater ammonia concentrations and the coupling between oceanic DMS and ammonia emissions, and biogeochemical cycling in Antarctic lakes and sub-glacial environments. The results obtained from the PTR-MS system during these investigations will advance understanding of aquatic biogeochemical processes and provide critical information on the rates of formation (or degradation) of a number of biogeochemically important compounds and the relative importance of critical biogeochemical pathways, at both cellular and ecosystem levels. This data will help refine global biogeochemical and climate models.