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Prof. Dr. Nicolas Brüggemann │IBG-3 Agrosphere │Foschungszentrum Jülich GmbH
Experience with isotope-specific laser instruments
IBG-3 Agrosphäre 213. Dezember 2010
Instruments used
TGA100A (Campbell Scientific): lab and fieldTGA200 (Campbell Scientific): labL1102-i (Picarro): lab
Experiments
Natural abundance measurementsTracer experiments (13CO2, H218O)
IBG-3 Agrosphäre 313. Dezember 2010
CO2 profiles soil respiration
Isotope-specific measurements of
Deep (30 cm) and shallow (2 cm) collars
IBG-3 Agrosphäre 413. Dezember 2010
The instrumentTDL instrument: TGA100A (Campbell Scientific, USA)
IBG-3 Agrosphäre 513. Dezember 2010“Chamber-in-chamber” system
Air inlet for soil chamber
Sample intake for ambient air
Soil chamber
IBG-3 Agrosphäre 613. Dezember 2010
δ13C of soil-respired CO2 in shaded and unshaded alpine grassland after 13CO2 pulse labelling: labelled plots
Bahn et al. (2009), New Phytologist 182: 451–460
IBG-3 Agrosphäre 713. Dezember 2010
…Picarro L1102-i …Campbell TGA200
Laboratory experiments with…
IBG-3 Agrosphäre 813. Dezember 2010
Experimental setup plant measurements
Norwayspruce
Grey poplar
IBG-3 Agrosphäre 913. Dezember 2010
Experimental setup soil measurements
IBG-3 Agrosphäre 1013. Dezember 2010
CalibrationTGAOne reference gas at high
concentration− TGA 100A: �20 vol%− TGA 200: �0.5-1 vol%
Usually two calibration tanks (tertiary standard), bracketing ambient CO2(higher conc for tracer applications)
− 325 ppm− 550-670 ppm
Traceable secondary standard from INSTAAR/CMDLCalibration frequency (automated)
− TGA 100A: every 10-15 min− TGA 200: every 3 min
PicarroManual switching between sample air
inlet and vaporizerManual start of the calibration with
liquid waterTwo-point calibrationPrimary standard from IAEAFrequency: �once per week
=> Calibration is now improved and automated in the new L2120-i
IBG-3 Agrosphäre 1113. Dezember 2010
Materials used
Synflex-1300 ¼‘‘ tubingStainless steel valves and fittingsStainless steel air humidifiers Stainless steel chambers for soil respiration measurementsPerspex chambers/cuvettes for lab experiments
Measurement frequency and averaging intervals
TGA100A: 10 Hz, averaging the last 30-45 s of a 90-100 s intervalTGA200: 10 Hz, averaging the last 10 s of a 20 s intervalPicarro: ? Hz, 15 s output (=averaging?) interval
IBG-3 Agrosphäre 1213. Dezember 2010
What do we want to know?What do we have to measure where and how often?
How to measure plant CO2 and H2O isofluxes continuously? Automated chambers?
How to measure soil moisture and CO2 profiles at all/continuously?How to integrate precipitation isotope measurements into your
ongoing H2O vapor measurements?
What does the ideally equipped isoflux field site look like?