Real-time quantification of oxygen isotope exchange between carbon dioxide and leaf/soil water with laser-based spectroscopy
The aim of the project is to characterize the degree of oxygen isotope exchange between carbon dioxide and leaf/soil water under varying environmental conditions, in various plant species and various soil types. This will contribute to a better understanding of the role of the terrestrial biosphere in the global carbon cycle as well as to partitioning ecosystem carbon dioxide fluxes into its components, as the oxygen isotopic signature of carbon dioxide allows the identification of the CO2 sources. The latest laser-based instruments for determining oxygen isotope ratios in carbon dioxide and water are used in laboratory and field experiments. In the laboratory experiments different environmental variables, such as temperature, air humidity, soil moisture and light intensity, are manipulated in a controlled manner, and the oxygen isotope signature of carbon dioxide and water are determined simultaneously. Field experiments will be performed with on-site application of the laser instruments. Finally, the observed data shall be incorporated into plant–soil models of biosphere–atmosphere carbon dioxide exchange.