Tracking the emergence oxygenic photosynthesis with metal isotopes: A case study from the Pongola Supergroup

用金属同位素追踪氧气光合作用的出现：来自 Pongola 超群的案例研究

• 批准号: 1144317
• 负责人: Noah Planavsky
• 金额: $ 12.75万
• 依托单位: Planavsky Noah J
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-06-01 至 2014-10-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1144317&HistoricalAwards=false
• 关键词: Tracking; emergence; oxygenic; photosynthesis; metal

Dr. Noah Planavsky has been awarded an NSF Earth Sciences Postdoctoral Fellowship in order to pinpoint the emergence of oxygenic photosynthesis, hosted by the California Institute of Technology. The chemical composition of the ocean has changed dramatically with the gradual oxidation of the Earth's surface. Undoubtedly the single most important event in Earth's progressive oxygenation was the development of oxygenic photosynthesis, which relies only on the ubiquitous molecules carbon dioxide and water, and allowed organisms to pioneer essentially every part of the Earth reached by sunlight. The success of this metabolism is reflected in the abundance of its waste product - molecular oxygen. Despite detailed investigations over the past 50 years, there is still intense debate about the timing of the evolution of oxygenic photosynthesis, with common estimates spanning over one billion years. The proposed work will use emerging heavy metal isotope systems to track the rise of oxygenic photosynthesis. In this study, unique properties of the molybdenum (Mo) and chromium (Cr) isotope systems will be utilized to shed light on manganese (Mn) cycling in the Earth's early oceans. Investigation of Mn oxidation is essential since other redox transformations (e.g., iron oxidation) may take place in oxygen-free conditions. The study will focus on rocks deposited from 3.2 to 2.5 billion years ago, spanning the range of time during which biological oxygen production is most typically predicted to have evolved. In addition, Dr. Planavsky will carry out educational activities by engaging undergraduate students in the investigation. Pinpointing the onset of oxygen production is central to understanding the tempo of biological evolution, and will provide important insights into planetary evolution in general. Further, given the importance of oxygenic photosynthesizers in controlling Earth's redox state and the carbon cycle, addressing the question of whether or not there was oxygen production in the mid-Archean will serve as a grounding point for understanding all major biogeochemical cycles on the early Earth.

诺亚·普兰夫斯基博士被授予美国国家科学基金会地球科学博士后奖学金，以查明由加州理工学院主办的氧气光合作用的出现。随着地球表面的逐渐氧化，海洋的化学成分发生了巨大的变化。毫无疑问，在地球逐渐氧合的过程中，最重要的事件是氧合光合作用的发展，它只依赖于普遍存在的二氧化碳和水分子，并允许有机体开拓地球上几乎每一个阳光能到达的地方。这种新陈代谢的成功体现在其废物--分子氧的丰富上。尽管在过去的50年里进行了详细的研究，但对于氧气光合作用的进化时间仍然存在激烈的争论，通常的估计跨度超过10亿年。这项拟议的工作将使用新兴的重金属同位素系统来跟踪氧气光合作用的上升。在这项研究中，钼(Mo)和铬(Cr)同位素体系的独特性质将被用来揭示地球早期海洋中的锰(Mn)循环。由于其他氧化还原反应(例如，铁氧化)可能在无氧条件下发生，因此对锰氧化的研究是必要的。这项研究的重点将是32亿到25亿年前沉积的岩石，跨越了通常预测的生物产氧进化的时间范围。此外，普拉夫斯基博士还将通过邀请本科生参与调查来开展教育活动。准确地确定氧气产生的开始是理解生物进化节奏的核心，并将提供对行星进化的总体上的重要见解。此外，鉴于产氧光合作用在控制地球氧化还原状态和碳循环方面的重要性，解决太古宙中期是否有氧气产生的问题将成为理解地球早期所有主要生物地球化学循环的基础。