光合作用群体在深度上的可变碳同位素分离在开放海洋的euphotic区域
Lillian C Henderson1, Fabian Wittmers2, Craig A Carlson3
1Department of Ocean Sciences, Rosenstiel School of Marine, Atmospheric, and Earth Science, University of Miami, Miami, FL 33149.
概括
海洋有机颗粒碳 (POC) 的起源是通过稳定的碳同位素来澄清的. 植物浮游生物群落的垂直变化在较低的euphotic区域显著影响碳同位素分离.
科学领域:
- 海洋生物地质化学海洋生物地质化学
- 海洋学 海洋学 海洋学
- 稳定同位素地球化学 稳定同位素地球化学
背景情况:
- 海洋有机颗粒碳 (POC) 在海洋碳出口,食物网和沉积过程中发挥着至关重要的作用.
- 表面和较低优光区 (LEZ) 之间的POC稳定碳同位素比率 (δ13C) 的变化表明光合作用社区或POC降解的变化.
- 了解POC的起源对于准确的碳循环建模和解释过去的海洋条件至关重要.
研究的目的:
- 研究在亚热带北大西洋中POC稳定碳同位素值和光合作用碳同位素分离 (εp) 的垂直变化.
- 确定光强度和植物浮游生物群体组成对 εp 的影响.
- 要区分光合作用和非光合作用材料对POC的同位素贡献.
主要方法:
- 在不同深度的植物和总POC中分析稳定的碳同位素比率 (δ13C).
- 测量光合作用碳同位素分离 (εp).
- 使用细胞计数数据来估计光合作用和非光合作用材料的比例.
主要成果:
- 植物醇的 δ13C 值随着深度显著下降,而 εp 增加.
- 这些 εp 的垂直变化与在主要的地质碳循环扰乱期间观察到的变化相当.
- 尽管 εp 的变化很大,但总POC 的 δ13C 值显示了较小的垂直差异 (2.7 ‰).
- 光合作用和非光合作用材料保持相对恒定的比例,但在LEZ中变得同位素上不同.
结论:
- 植物浮游生物群落的垂直结构和光线的可用性显著影响LEZ中的ep.
- 低温区域的光合作用可以影响出口和沉积有机碳的δ13C值,影响古海洋学解释.
- 目前的模型可能低估了垂直社区动态在光合作用碳同位素分离中的作用.
相关概念视频
01:14The Carbon Cycle
37.5K
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.
37.5K
01:04¹³C NMR: ¹H–¹³C Decoupling
1.1K
The probability of having two carbon-13 atoms next to each other is negligible because of the low natural abundance of carbon-13. Consequently, peak splitting due to carbon-carbon spin-spin coupling is not observed in spectra. However, protons up to three sigma bonds away split the carbon signal according to the n+1 rule, resulting in complicated spectra.
A broadband decoupling technique is used to simplify these complex, sometimes overlapping, signals. Broadband decoupling relies on a...
A broadband decoupling technique is used to simplify these complex, sometimes overlapping, signals. Broadband decoupling relies on a...
1.1K
01:46The Calvin Benson Cycle
4.5K
Ribulose 1,5- bisphosphate carboxylase/oxygenase (RuBisCo) is a critical enzyme that catalyzes carbon dioxide assimilation during photosynthesis. However, it is an inefficient enzyme, having an extremely slow catalytic rate. A typical enzyme can process about a thousand molecules per second; however, RuBisCo fixes only around three-carbon dioxides per second. Photosynthetic cells compensate for this slow rate by synthesizing very high amounts of RuBisCo, making it the most abundant single...
4.5K
01:40The Calvin Cycle
74.1K
Overview
74.1K
01:13Mass Spectrometry: Isotope Effect
2.1K
Most elements exist in nature as a mixture of isotopes. The isotopes differ in weight due to their respective number of neutrons. The molecular weight of a molecule is different depending on the specific isotope of its elements involved. As a result, the mass spectrum of the molecule exhibits peaks from the same fragment at multiple positions. The positions of these mass signals depend on the difference between the molecular mass. Furthermore, the intensity of these signals is dependent on the...
2.1K
01:10Carbon-13 (¹³C) NMR: Overview
5.7K
Carbon-13 is a naturally occurring NMR-active isotope of carbon with a low natural abundance of 1.1%. In contrast, carbon-12 is the most abundant isotope of carbon with zero nuclear spin. Therefore, it is NMR inactive. The gyromagnetic ratio of carbon-13 is smaller than that of protons. As a result, carbon-13 resonance is about 6000 times weaker than proton resonance. For a given magnetic field strength, the resonance frequency of carbon-13 is about one-fourth of the resonance frequency for...
5.7K