从恐龙牙上重建的中生代大气中的CO2度
Dingsu Feng1,2, Thomas Tütken3, Eva Maria Griebeler4
1Abteilung Geochemie & Isotopengeologie, Geowissenschaftliches Zentrum, Georg-August-Universität, Göttingen D-37077, Germany.
概括
化石恐龙牙揭示了过去大气中的二氧化碳 (CO2) 水平和全球植物生长. 牙面膜的三重氧同位素分析提供了对地球古代大气和生产力的洞察.
科学领域:
- 古气候学 古气候学
- 地质化学 地质化学
- 古生物学的古生物学
背景情况:
- 呼吸空气的脊椎动物将大气中的氧气 (O2) 纳入体水中.
- 在O2中的三氧同位素异常 (Δ'17Oair) 与大气中的二氧化碳 (pCO2) 和总初级产量 (GPP) 有关.
- 化石牙面膜保留了人体水的同位素特征,提供了过去环境条件的记录.
研究的目的:
- 通过对化石恐龙牙面膜的三氧同位素分析,证明重建过去大气pCO2和GPP的潜力.
- 建立牙面膜作为古大气气温室气体度和全球初级生产力的代理.
主要方法:
- 在未经改变的化石恐龙牙面膜样本中分析三重氧同位素组成 (Δ'17O).
- 利用体水中的Δ'17O与大气中的O2之间的关系,以及与pCO2和GPP的相关性.
- 将重建的pCO2和GPP值与中生时代的现有代理数据进行比较.
主要成果:
- 估计的平均罗纪晚期pCO2为1,200±150 ppmv,白纪晚期pCO2为750±200 ppmv.
- 重建的GPP比率 (GPPt/GPP0) 为1.20 ± 0.17的罗纪晚期和2.24 ± 0.96的白纪晚期,表明GPP比今天高出20-120%.
- 重建的值与其他古 CO2 代理数据有很好的一致性.
结论:
- 化石牙的三氧同位素分析提供了一种可行的方法来重建过去的大气pCO2.
- 牙面膜Δ'17O可以作为估计中生代GPP的代理,这表明全球初级生产率明显更高.
- 这种同位素方法为地球古代大气组成和生物圈功能提供了宝贵的见解.
相关概念视频
02:56The Fossil Record
25.6K
The fossil record documents only a small fraction of all organisms that have ever inhabited Earth. Fossilization is a rare process, and most organisms never become fossils. Moreover, the fossil record only exhibits fossils that have been discovered. Nevertheless, sedimentary rock fossils of long-lived, abundant, hard-bodied organisms dominate the fossil record. These fossils offer valuable information, such as an organism's physical form, behavior, and age. Studying the fossil record helps...
25.6K
01:50Global Climate Change
24.8K
Throughout its ~4.5 billion year history, the Earth has experienced periods of warming and cooling. However, the current drastic increase in global temperatures is well outside of the Earth’s cyclic norms, and evidence for human-caused global climate change is compelling. Paleoclimatology, the study of ancient climate conditions, provides ample evidence for human-caused global climate change by comparing recent conditions with those in the past.
24.8K
01:14The Carbon Cycle
39.8K
Carbon is the basis of all organic matter on Earth, and is recycled through the ecosystem in two primary processes: one in which carbon is exchanged among living organisms, and one in which carbon is cycled over long periods of time through fossilized organic remains, weathering of rocks, and volcanic activity. Human activities, including increased agricultural practices and the burning of fossil fuels, has greatly affected the balance of the natural carbon cycle.
39.8K
02:35What is Evolutionary History?
39.9K
Scientists record evolutionary history by analyzing fossil, morphological, and genetic data. The fossil record documents the history of life on Earth and provides evidence for evolution. However, both fossil and living organisms offer evidence that outlines Earth’s evolutionary history.
39.9K
01:12Carbon Skeletons
110.3K
Life on Earth is carbon-based, as all macromolecules that make up living organisms contain carbon atoms. All organic compounds have a carbon backbone. Each carbon atom is tetravalent and can bond with four other atoms, making it an extraordinarily flexible component of biological molecules. Because carbon’s valence electrons are stable, it rarely becomes an ion. As the carbon chain increases in length, structural modifications such as ring structures, double bonds, and branching side...
110.3K
02:48Radioactive Decay and Radiometric Dating
34.9K
Radioactivity is a spontaneous disintegration of an unstable nuclide and is a random process, as all the nuclei in the sample do not decay simultaneously. The number of disintegrations per unit time is called the activity (A), which is directly proportional to the number of nuclei in the sample. The decay constant (λ) is an average probability of decay per nucleus in unit time.
34.9K