18O- and 13C-monitoring of CO2

Four plant growth chambers are equipped with CO2- and H2O exchange systems (open mode) and connected to a on-line, continuous-flow stable isotope-ratio mass spectrometer.
The system allows monitoring of CO2 and H2O exchange of plant stands/mesocosms, and of the carbon and oxygen isotope composition of the CO2 exchanged with high temporal resolution (2 to 8 minutes) over extended periods of time (weeks to months). Growth chambers are connected to an IRMS (Finnegan Delta plus advantage) via a Gasbench II, so that the isotopic composition of inlet and outlet CO2 is measured on-line during gas exchange measurements.
The system includes gas mixing stations, which mix CO2-free air and tank-CO2 with known 13C- and 18O-composition. Thus, tracer studies at the mesocosm scale are conducted over extended periods. Such experiments include e.g. the on-line monitoring of the kinetics of label incorporation in respiratory CO2.
Studies can be conducted over a wide range of tightly controlled conditions of CO2 concentration (<100 ppm to >1000 ppm), vapor pressure deficit, irradiance, temperature and day lengths.
The system is operated automatically, and also includes a irrigation system.