Assessing the role of methanogens in driving Earth's oxygenation using Nickle isotopes

使用镍同位素评估产甲烷菌在驱动地球氧化中的作用

• 批准号: 1929725
• 负责人: Laura Wasylenki
• 金额: $ 7.64万
• 依托单位: Northern Arizona University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-04-15 至 2020-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1929725&HistoricalAwards=false
• 关键词: Assessing; role; methanogens; driving; Earth

The first substantial and long-lasting accumulation of oxygen in the atmosphere and surface waters of the oceans ~2.4 billion years ago was arguably one of the three most important turning points in the history of life, but exactly why and how this transformation took place remains poorly understood. One phenomenon that likely drove or at least stabilized the transition to a more oxidizing state was collapse of methanogens, a dominant form of life throughout much of the Archean Eon that sustained global anoxia through production of abundant methane. The objective of this project is to test the recent hypothesis of Konhauser et al. (2009; Nature 458, 750), who attributed the decline of methanogens to a shortage of nickel, an essential trace nutrient for these organisms. These authors argued that biogenic methane production might have waned well before the rise of oxygen, because oceanic Ni concentrations decreased substantially between 2.7 and 2.5 Ga. The recent discovery that modern methanogens strongly fractionate stable isotopes of Ni suggests that Ni limitation of methanogens may have left an isotopic fingerprint in the sedimentary record. The aim of this study is to analyze Ni isotope compositions of the same samples in which Konhauser et al. documented the Ni concentration decline, to see if an isotopic shift reflecting the onset of Ni limitation of methanogens is evident. Samples will be extracted from the hematite-rich layers of banded iron formations by microdrill, and isotopic compositions will be measured by MC-ICP-MS. Investigator will focus in particular on relationships between Ni concentrations and Ni isotopes for samples with ages between 2.8 and 2.3 billion years, the interval over which methanogens may or may not have assimilated increasingly large proportions of available dissolved Ni in seawater.

大约24亿年前，氧气在大气和地表水中的首次大量和持久的积累可以说是生命史上三个最重要的转折点之一，但这恰恰是为什么发生这种转变的原因和方式仍然不足。一种可能驱动或至少稳定过的现象，使甲烷植物的过渡过渡到氧化状态，这是甲烷植物的崩溃，这是整个大部分天使eon的主要生命形式，它通过产生丰富的甲烷而持续了全球缺氧。该项目的目的是检验Konhauser等人的最新假设。 （2009;自然458，750），他将甲烷剂的下降归因于镍短缺，这是这些生物的必不可少的痕量营养素。这些作者认为，生物甲烷的产生可能在氧气崛起之前已经逐渐减弱，因为海洋Ni浓度在2.7至2.5 ga之间大大降低。最近的发现，现代甲烷元的Ni稳定稳定的Ni同位素表明，NI的NI限制可能使甲基生物学的限制可能留在了同位素的塞剂录像中。这项研究的目的是分析Konhauser等人的相同样品的Ni同位素组成。记录了NI浓度下降，以了解反映甲烷元素限制的同位素转移是否明显。样品将通过微钻从带状铁的赤铁矿层中提取，同位素组成将通过MC-ICP-MS测量。研究人员将特别关注年龄在2.8至23亿年之间的样品的Ni浓度和Ni同位素之间的关系，这是甲烷元素可能会或可能不会吸收了越来越大的海水中可用溶解性NI的间隔。