Journal cover Journal topic
Biogeosciences An interactive open-access journal of the European Geosciences Union
Journal topic
Preprints
https://doi.org/10.5194/bg-2020-91
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/bg-2020-91
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Submitted as: research article 27 Mar 2020

Submitted as: research article | 27 Mar 2020

Review status
A revised version of this preprint was accepted for the journal BG and is expected to appear here in due course.

Leaf-scale quantification of the effect of photosynthetic gas exchange on Δ17O of atmospheric CO2

Getachew Agmuas Adnew1, Thijs L. Pons2, Gerbrand Koren3, Wouter Peters3,4, and Thomas Röckmann1 Getachew Agmuas Adnew et al.
  • 1Institute for Marine and Atmospheric research Utrecht (IMAU), Utrecht University, The Netherlands
  • 2Institute of Environmental Biology, UtrechtUniversity, The Netherlands
  • 3Department of Meteorology and Air Quality, Wageningen University, The Netherlands
  • 4Centre for Isotope Research, University of Groningen, The Netherlands

Abstract. Understanding the processes that affect the triple oxygen isotope composition of atmospheric CO2 during gas exchange can help constrain the interaction and fluxes between the atmosphere and the biosphere. We conducted leaf cuvette experiments under controlled conditions, using three plant species. The experiments were conducted at two different light intensities and using CO2 with different 17O-excess. The oxygen isotope composition of CO2 was used to estimate cm, the mole fraction of CO2 at the CO2-H2O exchange site. Our results demonstrate that two key factors determine the effect of gas exchange on the Δ17O of atmospheric CO2. The relative difference between Δ17O of the CO2 entering the leaf and the CO2 in equilibrium with leaf water, and the back-diffusion flux of CO2 from the leaf to the atmosphere, which can be quantified by the cm/ca ratio where ca is the CO2 mole fraction in the surrounding air. At low cm/ca ratio the discrimination is governed mainly by diffusion into the leaf, and at high cm/ca ratio by back-diffusion of CO2 that has equilibrated with the leaf water. Plants with a higher cm/ca ratio modify the Δ17O of atmospheric CO2 more strongly than plants with a lower cm/ca ratio. Based on the leaf cuvette experiments, the global value for discrimination against Δ17O of atmospheric CO2 during the photosynthetic gas exchange is estimated to be −0.57+/−0.14 ‰ using cm/ca values of 0.3 and 0.7 for C4 and C3 plants, respectively. The main uncertainties in this global estimate arise from variation in cm/ca ratios among plants and growth conditions.

Getachew Agmuas Adnew et al.

Interactive discussion

Status: closed
Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Printer-friendly Version - Printer-friendly version Supplement - Supplement

Interactive discussion

Status: closed
Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Printer-friendly Version - Printer-friendly version Supplement - Supplement

Getachew Agmuas Adnew et al.

Getachew Agmuas Adnew et al.

Viewed

Total article views: 278 (including HTML, PDF, and XML)
HTML PDF XML Total Supplement BibTeX EndNote
197 77 4 278 21 1 1
  • HTML: 197
  • PDF: 77
  • XML: 4
  • Total: 278
  • Supplement: 21
  • BibTeX: 1
  • EndNote: 1
Views and downloads (calculated since 27 Mar 2020)
Cumulative views and downloads (calculated since 27 Mar 2020)

Viewed (geographical distribution)

Total article views: 211 (including HTML, PDF, and XML) Thereof 209 with geography defined and 2 with unknown origin.
Country # Views %
  • 1
1
 
 
 
 

Cited

Saved

No saved metrics found.

Discussed

No discussed metrics found.
Latest update: 07 Jul 2020
Publications Copernicus
Download
Short summary
We measured the effect of photosynthesis, the largest flux in the carbon cycle, on the triple oxygen isotope composition of atmospheric CO2 at the leaf level during gas exchange using three plant species. The main factors that limit the impact of land vegetation on the triple oxygen isotope composition of atmospheric CO2 are identified, characterized and discussed. The effect of photosynthesis on the isotopic composition of CO2 is commonly quantified as discrimination (ΔA).
We measured the effect of photosynthesis, the largest flux in the carbon cycle, on the triple...
Citation