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Response of the Nitrogen Cycle to Ocean Redox Chemistry During the Great Oxidation Event

大氧化事件期间氮循环对海洋氧化还原化学的响应

基本信息

批准号：
NE/H016805/1
负责人：
Aubrey Zerkle
金额：
$ 35.42万
依托单位：
Newcastle University
依托单位国家：
英国
项目类别：
Fellowship
财政年份：
2010
资助国家：
英国
起止时间：
2010 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=NE%2FH016805%2F1
关键词：
Response Nitrogen Cycle Ocean Redox

项目摘要

One of the most fundamental questions that drives natural sciences is how life evolved on Earth. Understanding how life evolved on this planet also informs our search for habitable planets in other solar systems. What we now know beyond a reasonable doubt is that simple single-celled organisms evolved in the ocean greater than 3 billion years ago. We also know that the chemistry of the Earth's surface (both the atmosphere and the oceans) has undergone dramatic changes since that first cell division occurred. What we then seek to understand is how the evolution of life has responded to, and in some cases driven, these changes in Earth surface chemistry. Understanding how life responded to geochemical changes on the planet in the past will additionally help us to more clearly predict how life will respond to chemical changes in the future, for example associated with rapidly approaching climate change. One of the major parameters that affects life in the ocean is the availability of dissolved oxygen, which is not only essential for all higher life forms to exist, but also directly controls the distribution and abundance of essential elements that make up the building blocks of life. For the first ~3.5 billion years of Earth history, the ocean was characterized by a lack of dissolved oxygen, a situation known as anoxia. Oxygen first began to build up in the atmosphere and oceans between ~2.4 and 2.3 billion years ago, in perhaps the most dramatic event in the history of Earth surface chemistry, termed the Great Oxidation Event. It was not until ~580 million years ago that oxygen levels in the atmosphere rose sufficiently to completely oxygenate the oceans. In the intervening ~2 billion years, the chemistry of the oceans fluctuated rapidly between various levels of oxygenation. Thus a major focus for scientific research recently has been on identifying and understanding the response of biology and the cycling of essential nutrients to variable amounts of oxygen in the environment. Nitrogen is an essential element in all living organisms, required along with carbon and phosphorus for the formation of proteins, amino acids, DNA and RNA. The distribution of nitrogen in the biosphere is controlled by biological reactions that respond to environmental parameters, including the amount of available oxygen. Despite the importance of nitrogen to life, very little is known about how the nitrogen cycle responded to fluctuations in oxygen concentrations over Earth history. The aim of this project is specifically to interpret the response of the global nitrogen cycle to changes in the oxygen content of the atmosphere and oceans during the Great Oxidation Event. This will be accomplished by laboratory experiments with microorganisms that are important in the modern nitrogen cycle, and application of the results of the experimental studies to the investigation of nitrogen and indicators of oxygenation in sedimentary rocks spanning the Great Oxidation Event.

推动自然科学发展的最基本问题之一是地球上的生命是如何进化的。了解生命在这颗行星上如何演化也为我们寻找其他太阳系中的宜居行星提供了信息。我们现在毫无疑问地知道，简单的单细胞生物在 30 亿多年前就在海洋中进化了。我们还知道，自从第一次细胞分裂发生以来，地球表面（包括大气和海洋）的化学成分已经发生了巨大的变化。然后，我们试图了解生命的进化如何响应并在某些情况下驱动地球表面化学的这些变化。了解生命过去如何应对地球上的地球化学变化还将帮助我们更清楚地预测生命将如何应对未来的化学变化，例如与迅速逼近的气候变化相关的化学变化。影响海洋生命的主要参数之一是溶解氧的可用性，它不仅对所有高等生命形式的存在至关重要，而且还直接控制构成生命基石的基本元素的分布和丰度。在地球历史的最初约 35 亿年里，海洋的特点是缺乏溶解氧，这种情况被称为缺氧。大约 2.4 至 23 亿年前，氧气首次开始在大气和海洋中积聚，这可能是地球表面化学史上最引人注目的事件，被称为“大氧化事件”。直到约 5.8 亿年前，大气中的氧气含量才上升到足以完全为海洋供氧的程度。在接下来的约 20 亿年里，海洋的化学成分在不同的含氧水平之间快速波动。因此，最近科学研究的一个主要焦点是识别和理解生物学的反应以及必需营养素对环境中不同数量的氧气的循环。氮是所有生物体的必需元素，与碳和磷一起形成蛋白质、氨基酸、DNA 和 RNA。生物圈中氮的分布是由响应环境参数（包括可用氧气量）的生物反应控制的。尽管氮对生命很重要，但我们对地球历史上氮循环如何响应氧浓度波动知之甚少。该项目的目的是专门解释大氧化事件期间全球氮循环对大气和海洋氧含量变化的响应。这将通过对现代氮循环中重要的微生物进行实验室实验，并将实验研究的结果应用于跨越大氧化事件的沉积岩中的氮和氧合指标的调查来完成。