The role of organic and metal cofactors on the biogenic synthesis of halogenated volatile hydrocarbons

有机和金属辅助因子对卤代挥发性烃生物合成的作用

• 批准号: 1559276
• 负责人: Sergio Sanudo-Wilhelmy
• 金额: $ 68.1万
• 依托单位: University of Southern California
• 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: 2016-04-01 至 2020-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1559276&HistoricalAwards=false
• 关键词: role; organic; metal; cofactors; biogenic

Volatile halogenated hydrocarbon gases, in this case halomethanes, are produced naturally by organisms in the ocean; which then serves as a source of these biogenic gases to the atmosphere. Their chemical reactions in the atmosphere are very similar to those of anthropogenic chlorofluorocarbons (CFCs). While CFCs are well-studied because they consume the ozone in the upper atmosphere that shields the earth from harmful ultraviolet radiation, halomethanes have been largely neglected, even though they currently account for 25% of the ozone depletion. As anthropogenic CFC levels steadily decline, however, halomethanes are predicted to account for 50% of ozone depletion by 2050. Based on limited study thus far, marine halomethane production has been ascribed mainly to phytoplankton and macro algae. This project will build on new and compelling data that suggests marine heterotrophic bacteria could also be major producers of halomethanes. The data produced here will provide the critical evaluation required to address discrepancies in global halomethane budgets which currently are out of balance due to an unknown source to the atmosphere, evaluating the hypothesis that marine heterotrophic bacteria can supply this missing source. Concerns over the stability of the earth's stratospheric ozone layer make this valuable and necessary research with added value of providing support for engaged undergraduate, graduate, and postdoctoral education at the University of Southern California.Past research on the production of marine halomethanes has focused on phytoplankton and macro algae, while potential bacterial contributions to the processe have been neglected. This research proposes to study the role of marine heterotrophic bacteria on the production of halomethanes. It has been noted in past studies that there are discrepancies in the global atmospheric halomethane budget, and it is possible this is due to a large missing bacterial source. Additionally, this research will evaluate the potential importance of vitamin B12, methionine, and vanadium cofactors on the synthesis of halomethanes in bacteria. A large portion of marine bacteria cannot synthesize methylation co-enzymes, and therefore, would require available B12, methionine, and vanadium from external sources to complete the methylation step. This study will also measure concentrations of halomethanes, B12, methionine, and vanadium in upwelling regions as well as at a long-term time series site in order to put constraints on the variability of halomethanes concentrations for use in global linked air-sea models.

挥发性卤代烃气体（在本例中为卤代甲烷）是由海洋生物自然产生的；然后作为这些生物气体排放到大气中的来源。它们在大气中的化学反应与人为的氯氟烃（CFC）的化学反应非常相似。虽然氟氯化碳因消耗高层大气中的臭氧而受到广泛研究，从而保护地球免受有害的紫外线辐射，但卤代甲烷在很大程度上被忽视了，尽管它们目前占臭氧消耗的 25%。 然而，随着人为氟氯化碳水平稳步下降，预计到 2050 年，卤代甲烷将占臭氧消耗的 50%。根据迄今为止有限的研究，海洋卤代甲烷的产生主要归因于浮游植物和大型藻类。该项目将建立在令人信服的新数据的基础上，这些数据表明海洋异养细菌也可能是卤代甲烷的主要生产者。 这里产生的数据将提供解决全球卤甲烷预算差异所需的关键评估，目前全球卤甲烷预算由于大气来源未知而失衡，评估海洋异养细菌可以提供这一缺失来源的假设。对地球平流层臭氧层稳定性的担忧使得这项研究变得有价值和必要，并为南加州大学的本科生、研究生和博士后教育提供支持。过去有关海洋卤甲烷产生的研究主要集中在浮游植物上和大型藻类，而细菌对该过程的潜在贡献却被忽视了。本研究旨在研究海洋异养细菌在卤代甲烷生产中的作用。过去的研究指出，全球大气卤甲烷预算存在差异，这可能是由于细菌来源大量缺失造成的。此外，这项研究还将评估维生素 B12、蛋氨酸和钒辅助因子对细菌合成卤代甲烷的潜在重要性。大部分海洋细菌无法合成甲基化辅酶，因此需要外部来源的 B12、蛋氨酸和钒来完成甲基化步骤。这项研究还将测量上升流区域以及长期时间序列站点的卤代甲烷、B12、蛋氨酸和钒的浓度，以便限制卤代甲烷浓度的变异性，用于全球关联的海气模型。