Book contents
- Frontmatter
- Contents
- Preface
- List of symbols
- 1 The general nature of biosphere-atmosphere fluxes
- 2 Thermodynamics, work, and energy
- 3 Chemical reactions, enzyme catalysts, and stable isotopes
- 4 Control over metabolic fluxes
- 5 Modeling the metabolic CO2 flux
- 6 Diffusion and continuity
- 7 Boundary layer and stomatal control over leaf fluxes
- 8 Leaf structure and function
- 9 Water transport within the soil-plant-atmosphere continuum
- 10 Leaf and canopy energy budgets
- 11 Canopy structure and radiative transfer
- 12 Vertical structure and mixing of the atmosphere
- 13 Wind and turbulence
- 14 Observations of turbulent fluxes
- 15 Modeling of fluxes at the canopy and landscape scales
- 16 Soil fluxes of CO2, CH4, and NOx
- 17 Fluxes of biogenic volatile compounds between plants and the atmosphere
- 18 Stable isotope variants as tracers for studying biosphere-atmosphere exchange
- References
- Index
- Plate Section
18 - Stable isotope variants as tracers for studying biosphere-atmosphere exchange
Published online by Cambridge University Press: 05 June 2014
- Frontmatter
- Contents
- Preface
- List of symbols
- 1 The general nature of biosphere-atmosphere fluxes
- 2 Thermodynamics, work, and energy
- 3 Chemical reactions, enzyme catalysts, and stable isotopes
- 4 Control over metabolic fluxes
- 5 Modeling the metabolic CO2 flux
- 6 Diffusion and continuity
- 7 Boundary layer and stomatal control over leaf fluxes
- 8 Leaf structure and function
- 9 Water transport within the soil-plant-atmosphere continuum
- 10 Leaf and canopy energy budgets
- 11 Canopy structure and radiative transfer
- 12 Vertical structure and mixing of the atmosphere
- 13 Wind and turbulence
- 14 Observations of turbulent fluxes
- 15 Modeling of fluxes at the canopy and landscape scales
- 16 Soil fluxes of CO2, CH4, and NOx
- 17 Fluxes of biogenic volatile compounds between plants and the atmosphere
- 18 Stable isotope variants as tracers for studying biosphere-atmosphere exchange
- References
- Index
- Plate Section
Summary
Rural air samples were all collected from the layer of air close to the ground . . . under circumstances where the metabolic activity of plants might be expected to influence the carbon dioxide composition of the air. This is so because plants exchange carbon dioxide with the atmosphere by means of respiration and assimilation and also because carbon dioxide is evolved from the ground through decay of organic material in the soil and respiration of plant roots . . . Thus the relationship between carbon isotope ratio and molar concentration observed for the carbon dioxide of rural air is explained if carbon dioxide is added to or subtracted from the atmosphere by plants or their decay products.
Charles Keeling (1958), Scripp Institution of OceanographyOf the 98 naturally occurring elements on earth, 18 are known to be radioactive, meaning that they exhibit time-dependent decay to lighter elements, and 80 are known to be stable. Of those 80 stable elements, 54 are known to exhibit isotopic variation, meaning that atoms within the same elemental category have different atomic masses due to variations in neutron number (Section 3.5). Given the dependency of diffusive flux on atomic mass, molecules of the same compound, but composed of different isotopes, will diffuse at different rates and thus segregate into isotopic fractions over time. Analysis of isotopic fractionation provides researchers with one of their most valuable tools for understanding rates of diffusive flux, enzyme-substrate interactions, interactions among metabolic pathways, and the sources and sinks of compounds used for various biogeochemical processes, even extending beyond those defined solely by diffusion. Of particular importance have been analyses of the isotopic composition of CO2 and H2O, given that C, H, and O are among those 54 elements that exhibit stable isotope variation.
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- Chapter
- Information
- Terrestrial Biosphere-Atmosphere Fluxes , pp. 415 - 433Publisher: Cambridge University PressPrint publication year: 2014