Simultaneous measurement of δ13C-CO2, δ18O-CO2 and δ17O-CO2 in atmospheric samples First results of the Aerodyne Dual-Laser Absorption Spectrometer at the Centre for Isotope Research
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1. The document describes a new spectrometer at the Centre for Isotope Research that can simultaneously measure the stable isotopes of carbon (δ13C) and oxygen (δ18O and δ17O) in atmospheric CO2 samples without needing to extract the CO2. 2. Initial results from atmospheric samples measured at the Lutjewad monitoring station in the Netherlands show relationships between δ17O and δ18O that can provide insights into carbon cycle processes. 3. Measurements of the "excess 17O" parameter in samples suggest the spectrometer could be used to study the impacts of fossil fuel combustion and biosphere productivity on atmospheric CO2 levels.
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Simultaneous measurement of δ13C-CO2, δ18O-CO2 and δ17O-CO2 in atmospheric samples First results of the Aerodyne Dual-Laser Absorption Spectrometer at the Centre for Isotope Research
- 1. Simultaneous measurement of δ13C-CO2, δ18O-CO2 and δ17O-CO2 in atmospheric samples First results of the Aerodyne Dual-Laser Absorption Spectrometer at the Centre for Isotope Research P.M. Steur1, H. A. Scheeren1, D.D. Nelson2, J. D. Hooghiem1, H. Chen1, H.A.J. Meijer1 1Centre for Isotope Research (CIO), University of Groningen, the Netherlands 2 Aerodyne Research, Inc., Billerica (MA), USA E-mail: p.m.steur@rug.nl
- 2. Simultaneous measurement of δ13C-CO2, δ18O-CO2 and δ17O-CO2 in atmospheric samples First results of the Aerodyne Dual-Laser Absorption Spectrometer at the Centre for Isotope Research P.M. Steur1, H. A. Scheeren1, D.D. Nelson2, J. D. Hooghiem1, H. Chen1, H.A.J. Meijer1 1Centre for Isotope Research (CIO), University of Groningen, the Netherlands 2 Aerodyne Research, Inc., Billerica (MA), USA E-mail: p.m.steur@rug.nl Contents: 1. Atmospheric measurement station Lutjewad and stable isotope measurement monitoring (until recent) 2. The new spectrometer for 13C, 18O and 17O measurements 3. The potential of 17O- 18O relation for carbon cycle research 4. First results of the new spectrometer at CIO
- 3. Lutjewad monitoring data (flasks)
- 4. Lutjewad monitoring data (flasks)
- 5. Lutjewad monitoring data (flasks)
- 6. Lutjewad atmospheric measurement station • Set up in 2000 by the Centre of Isotope Research • 60 meters high • Located at the coast of the Wadden Sea: - Northern winds background signal - Southern wind anthropogenic and biogenic sources and sinks
- 7. Atmospheric measurements on sample flasks • Every 3 days a flask is filled using an automated sampling system • Flasks are analyzed for CO2, CH4,CO concentration on GC • Atmospheric CO2 is analyzed for 13C and 18O on IRMS (until recently) • CO2 extraction needed Automatic flask sampling system at Lutjewad atmospheric measurement station
- 8. CIO-DL-SICAS • 13C, 18O and 17O of atmospheric CO2 • Directly on dry air samples • Sample size: 130mL of air per flask • Precision SICAS for n=8 measurements of sample/reference : - Del636 -> 0.02 per mill - Del628 -> 0.02 per mill - Del627-> 0.04 per mill • Calibration is still work in progress Schematic of inside of the SICAS (upper) and photgraph of inside of the SICAS (lower)
- 9. Lutjewad flasks measured (SICAS measurements in red)
- 10. 17O-18O relation in the troposphere CO2-water equilibration line: 17O +1 = ( 18O+1) 0.528
- 11. 17O-18O relation in the troposphere CO2-water equilibration line: 17O +1 = ( 18O+1) 0.528 Excess 17O: Δ17OCO2 = ln( 17O + 1 ) – 0.528 ln ( 18O + 1)
- 12. 17O-18O relation in the troposphere Simplified box model of CO2 fluxes relevant for Δ17OCO2 variations in the troposphere. Adapted from Luz et al., 1999 Stratosphere Δ17OCO2 >> 0 Biosphere: Δ17OCO2 = 0 Oceans and surface waters: Δ17OCO2 = 0 Troposphere Δ17OCO2 = ? respiration CO2-water equilibration line: 17O +1 = ( 18O+1) 0.528 Excess 17O: Δ17OCO2 = ln( 17O + 1 ) – 0.528 ln ( 18O + 1)
- 13. 17O -18O relation of first air samples measured with SICAS Relation d17O over d18O, different colours indicate different locations. Dotted line indicates meteoric water line with slope = 0.528. Slope=0.528
- 14. Δ17OCO2 relation of first air samples measured with SICAS Excess 17O (per meg) over CO2 concentrations, different colours indicate different locations.
- 15. Δ17OCO2 relation of first air samples measured with SICAS Excess 17O (per meg) over CO2 concentrations, different colours indicate different locations.
- 16. Δ17OCO2 relation of first air samples measured with SICAS Horváth et al., 2012 Measured Δ17OCO2 from fossil fuel combustion: Natural gas = -300 per meg Car exhaust = -320 per meg Excess 17O (per meg) over CO2 concentrations, different colours indicate different locations.
- 17. Δ17OCO2 relation of first air samples measured with SICAS Excess 17O (per meg) over CO2 concentrations, different colours indicate different locations.
- 19. Evaluation and outlook • Stable and high precision measurements of 13C, 18O and 17O without the need for extraction • Potential for using 17O and 18O for carbon cycle research • Calibration of the SICAS is ongoing work
- 20. References • Horváth, B., Hofmann, M. E. G. and Pack, A.: On the triple oxygen isotope composition of carbon dioxide from some combustion processes, Geochim. Cosmochim. Acta, 95, 160–168, doi:10.1016/j.gca.2012.07.021, 2012. • Luz, B., Barkan, E. and Bender, M. L.: Triple-isotope composition of atmospheric oxygen as a tracer of biosphere productivity, , 547–550, 1999.
Editor's Notes
- At CIO we have been monitoring the CO2 concentration and stable isotope composition of the air at our own atmospheric measurement station for many years already. These graphs show the result of this monitoring. The seasonal cycles, caused by plant activity are clearly visible in both the concentration as the isotopes. With high plant activity, co2 concnetrations are low and d13C and f18O are more enriched. Anthtopogenic signals are captured in the very high concentrations which are also very depleted in d13C. Also, a long-term increase of CO2 concentration in the atmosphere is visible. After 2016 stable isotope measurements have not been conducted anymore, due to the high costs of the measurements.
- At CIO we have been monitoring the CO2 concentration and stable isotope composition of the air at our own atmospheric measurement station for many years already. These graphs show the result of this monitoring. The seasonal cycles, caused by plant activity are clearly visible in both the concentration as the isotopes. With high plant activity, co2 concnetrations are low and d13C and f18O are more enriched. Anthtopogenic signals are captured in the very high concentrations which are also very depleted in d13C. Also, a long-term increase of CO2 concentration in the atmosphere is visible. After 2016 stable isotope measurements have not been conducted anymore, due to the high costs of the measurements.
- At CIO we have been monitoring the CO2 concentration and stable isotope composition of the air at our own atmospheric measurement station for many years already. These graphs show the result of this monitoring. The seasonal cycles, caused by plant activity are clearly visible in both the concentration as the isotopes. With high plant activity, co2 concnetrations are low and d13C and f18O are more enriched. Anthtopogenic signals are captured in the very high concentrations which are also very depleted in d13C. Also, a long-term increase of CO2 concentration in the atmosphere is visible. After 2016 stable isotope measurements have not been conducted anymore, due to the high costs of the measurements.
- I want to start telling something about some of the work that has been done regarding stable isotope measurements in atmospheric CO2 at CIO. A great part of this has been the mornitoring of CO2 concnetrations and isotopic composition from air sampled at Lutjewad, the measurement station of CIO set up in 2000. The tower of the measurement station is 60 meters high and located at the coast of the Wadden Sea in the North of the Netherlands. So, roughly this gives a Middle European background signal with Norther winds, and with Southern winds the signal is dominated by anthropogenic and biogenic sources and sinks.
- For stable isotope measurements, air samples are taken every 3 days with an automated sampling system. These flasks are taken to the lab in Groningen for analysis of trace gases, as CO2, CH4, and CO and for stable isotope analysis. This has always been done using IRMS (Isotope-Ratio Mass Spectrometry), and d13C and d18O of CO2 were measured.
- Since 2017 there is a laser spectrometer, the CIO-DL-SICAS, available at the CIO. This dual laser spectrometer, operating in the Mid Infra Red, is developed to measure stable isotopes in atmospheric CO2. The great advantage of a seconds laser is that it enables us to measure d17O as well, besided d13C and d18O. Very short how the spectrometer works: the lasers, operating in mid infrared at very specific frequencies, are send through an optical cell, containing the air sample to be measured. The four isotopologues of CO2 absorb energy from the lasers, and this absorbtion is detected.
- It is now easier to measure stable isotope composition of the flasks collected at Lutjewad, and here you see the fist results of the SICAS measurments in red. We continued where the IRMS stopped with the Lutjewad data. Although calibration of the stable isotope values is still work in progress, we can see that the trends of seasonal change are clearly captured in the isotopeic compositions, which indicates that this new method is suitable for measuring the variations in d13C and d18O in atmospheric CO2.
- Besides d13C and d18O the SICAS also measured d17C. In this slide I will try to explain the the potential for a new tracer for plant activity, or gross primary production, using the the ratio of 17O over 18O of atmospheric CO2. Before I can do this, I need to explain some definitions: First of all, CO2 that is equilibrated with water, has a constant 17O-18O relation due to mass fractionation. This relation is 17O +1 = ( 18O+1) 0.528
- The capital delta 17O, or excess 17O, is defined based on this relation. So excess 17O is a measure for the deviation of the 17O 18O composition in CO2 from the water mass fractionation line.
- Measuring the excess 17O has great potential for carbon cycle research, due to different processes that influence this excess 17O. To understand this we need to know what is affecting the 17O/18O ratio in the troposphere, the site we are usually sampling. This ratio is affected by several natural processes, but mostly by equilibration of CO2 with water, both in plants and on ocean surfaces and surface waters. CO2 that is equilibrated with water will have a excess 17O of 0. Another process that influences the 17O/18O ratio in the troposphere, is intrusion of CO2 from the stratosphere. Stratospheric CO2 has a very large excess 17O signal, so CO2 is highly enriched in 17O compared to the mass fractionation line of water. This is due to photochemical transfer of 17O and 18O from O2 to CO2 in the presence of O3. During this reaction mass independent fractionation causes higher abundances of 17O in CO2.
- In this graph the first results of the d17O and d18O values measured on atmospheric air samples with the SICAS are shown. The natural logaritms of the delta values +1 are plotted, to show the slope of the values in comparison with the water mass fractionation line. The different colours indicate different sample site. There are samples from Antarctica (Hally Bay) , F3, Lutjewad, Mace Head (west coast of Ireland) and stratospheric samples. The dotted line has a slope of 0.528, to show how well the values fit on this meteoric water line. The first thing that stands out are the stratospheric samples, that do not follow this meteoric water line, but are mainly situated above this line, as we would expect. Tabel niet laten zien, maar wel excels 17O tegenover CO2 concentratie
- Here the same data,
- Here the same data,
- Here the same data,