Brüggemann, N.

Butterbach-Bahl, K.

Papen, H.

Steigner, D.

KITopen

KIT – a cooperation betweenKarlsruhe Research Centerand University of KarlsruheDiurnal and Seasonal Variation of δ13C and δ18O of Carbon Dioxide in a Norway Spruce Forest Measured with a Tunable Diode Laser Absorption SpectrometerN. Brüggemann, H. Papen, D. Steigner, K. Butterbach-BahlCenter of Stable Isotopes, Forschungszentrum Karlsruhe, Institute of Meteorology and Climate Research (IMK-IFU), Kreuzeckbahnstrasse 19, D-82467 Garmisch-PartenkirchenContact: Dr. Nicolas Brüggemann (nicolas.brueggemann@imk.fzk.de)Tel.: +49-(0)8821-183226, Fax: +49-(0)8821-183294time of day [CET]0 3 6 9 12 15 18 21 24δ18 O [‰ vs. SMOW]121314152m 8m 15m 50m δ13 C [‰ vs. PDB]-11-10-9-8-72m 8m 15m 50m CO2 [ppm]3603804004204404602m 8m 15m 50m time of day [CET]0 3 6 9 12 15 18 21 24time of day [CET]0 3 6 9 12 15 18 21 24Dec-Feb Mar-May Jun-Jul10111213141516-505101520050100150200250δ18O [‰ vs. SMOW]air temp 2 m [°C]global radiation [W m -2]10 11 12 13 14 15 16 -11.5-11.0-10.5-10.0-9.5-9.0-8.5-8.0-7.5-505101520050100150200250δ13 C [‰ vs. PDB]air temp 2 m [°C]global radiation [W m -2]-11.5 -11.0 -10.5 -10.0 -9.5 -9.0 -8.5 -8.0 -7.5 date1.12.07 1.1.08 1.2.08 1.3.08 1.4.08 1.5.08 1.6.08 1.7.08 1.8.08δ18 O [‰ vs. SMOW]1012141610121416δ13 C [‰ vs. PDB]-14-12-10-8-14-12-10-8CO2 [ppm]3603804004204404604803603804004204404604802m 8m 15m 50m precipitation [mm]0102030temperature [°C]-1001020wind speed [m s-1]02468precipitationair temperature (2 m) wind speed 50 mglobal radiation [W m-2]0100200300400relative humidity [%]405060708090100Global radiationrelative air humiditydate1.4.08 1.5.08 1.6.08 1.7.08 1.8.08δ18 O [‰ vs. SMOW]-16-12-8-404-16-12-8-404total soil respirationheterotrophic soil respirationδ13 C [‰ vs. PDB]-34-32-30-28-26-34-32-30-28-26total soil respirationheterotrophic soil respirationrespiration rate[µmol CO2 m-2 s-1]0123401234total soil respirationheterotrophic soil respirationprecipitation [mm]0102030temperature [°C]0510152025wind speed [m s-1]02468precipitationair temperature (2 m) wind speed (above canopy) global radiation [W m-2]0100200300400relative humidity [%]405060708090100Global radiationjulian day vs rh_2m -29.5-29.0-28.5-28.0-27.5-27.0-26.5510152050100150200250δ13 C [‰ vs. PDB]air temp 2 m [°C]global radiation [W m -2]-29.5-29.0-28.5-28.0-27.5-27.0-26.5510152050100150200250δ13 C [‰ vs. PDB]air temp 2 m [°C]global radiation [W m -2]-29.5 -29.0 -28.5 -28.0 -27.5 -27.0 -26.5 -8-6-4-20510152050100150200250300δ18 O [‰ vs. SMOW]air temp 2 m [°C]global radiation [W m -2]-8 -6 -4 -2 0 -8-6-4-20510152050100150200250300δ18 O [‰ vs. SMOW]air temp 2 m [°C]global radiation [W m -2]I. BackgroundUnderstanding the role of terrestrial ecosystems in governing the isotopic composition of atmospheric CO2 requires knowledge of diurnal and seasonal variations of δ13C and δ18O of CO2 in biosphere-atmosphere CO2 exchange. Tunable diode laser absorption spectroscopy (TDLAS) has recently led to great advances in stable isotope ecosystem research, as it allows for measuring stable isotope ratios in trace gases and water with an unprecedented time resolution also in the field. Here we present several months of data on mixing ratios, δ13C and δ18O of CO2 at different heights and on respiration rates and δ13C and δ18O of CO2 from heterotrophic and total soil respiration in a Norway spruce forest (Höglwald) close to Augsburg, Germany. II. MethodCO2 mixing ratios as well δ13C and δ18O of CO2 were measured with a TGA100A (Campbell Scientific, USA), equipped with sampling manifold, sample pump, flow controller and air driers. Air was sampled within (2, 8, 15 m) and above the forest canopy (50 m), and total and heterotrophic soil respiration was measured close to the tower with three custom-made stainless steel chambers each, equipped with an inlet, an outlet and a vent to avoid pressure differences between inside and outside (see image at the right). Total and heterotrophic soil respiration chambers were placed on stainless steel rings of 2 and 30 cm depth, respectively, to include or to exclude roots. Rainwater was collected with a funnel and led into the chambers through a small PTFE tube. Inlet air for the chambers was provided from a 50 L buffer tank that was continuously filled by a pump with ambient air taken at 1 m height. Each height and each soil respiration chamber was sampled once within 30 min for 100 sec, of which the last 45 sec were taken as averaging period. Two reference gases (325 and 552 ppm CO2 in air) were sampled every 15 min to monitor instrument drift.III. Seasonal variation of mixing ratios,  δ13C and δ18O of ecosystem CO2 IV. Seasonal variation of release, δ13C and δ18O of soil-respired CO2V. Diurnal variation of δ13C and δ18O of ecosystem CO2 VI. Diurnal variation of δ13C and δ18O of soil-respired CO2time of day [CET]0 3 6 9 12 15 18 21 24-8-6-4-2total soil respirationheterotrophic soil respirationδ13 C [‰ vs. PDB]-30-29-28-27total soil respirationheterotrophic soil respirationrespiration rate [µmol m-2 s-1]1.01.52.02.53.03.54.0total soil respirationheterotrophic soil respirationδ18 O [‰ vs. SMOW]time of day [CET]0 3 6 9 12 15 18 21 24Apr-May Jun-JulVII. SummaryEcosystem CO2:• Mean CO2 mixing ratios were highest in winter and lowest in summer, δ13C and δ18O of CO2 were lowest in winter and highest in summer• Winter: δ13C and δ18O mirrored well the temporal variation in CO2 mixing ratios and were closely correlated. Diurnal variation of all three variables was low.• Spring/Summer: decoupling of δ13C and δ18O, with δ18O following more closely changes in air temperature and global radiation than δ13C. Diurnal variation was more pronounced, in summer even more than in spring.Soil respiration:• The daily maximum of total soil respiration occurred around 7 pm CET, the daily maximum of heterotrophic soil respiration around 4 pm CET.• Spring: Total respiration rates were on average only slightly higher than heterotrophic respiration rates. The δ13Cheterotrophic was on average c. 1 ‰higher than the δ13Ctotal. The δ18Ototal was on average c. 3 ‰ lower than the δ18Oheterotrophic. • Summer: Total respiration rates were on average almost twice as high as heterotrophic respiration rates. The difference between δ13Cheterotrophic and δ13Ctotal had almost vanished. The difference between δ18Oheterotrophic and δ18Ototal was reversed, with δ18Ototal being more positive.δ13C [‰ vs. PDB]-14 -12 -10 -8δ18 O [‰ vs. SMOW]10121416δ13C [‰ vs. PDB]-14 -12 -10 -8δ13C [‰ vs. PDB]-14 -12 -10 -8R2 = 0.87P < 0.0001R2 = 0.04P > 0.05R2 = 0.20P = 0.0015Dec-Feb Mar-May Jun-JulFig. 1. Daily mean values of meteorological parameters (precipitation = daily sum), of CO2 mixing ratios and δ13C and δ18O of CO2 in and above the canopy of a Norway spruce forest (Höglwald, Southern Germany) (n = 48, ± s.e.). Fig. 2. 3-D-fit (Loess) of the dependencies of δ13C (a) and δ18O (b) of ecosystem CO2 on global radiation and air temperature at 2 m height.Fig. 3. Correlation of daily mean δ13C and δ18O of ecosystem CO2 in winter, spring and summer.baFig. 4. Daily mean values of meteorological parameters (precipitation = daily sum), of total and heterotrophic soil respiration rates and of δ13C and δ18O of soil-respired CO2 (n = 48, ± s.e.).Fig. 5. 3-D-fit (Loess) of the dependencies of δ13C (a, b) and δ18O (c, d) of CO2 from total (a, c) and heterotrophic (b, d) respiration on global radiationand air temperature at 2 m height.a bc dFig. 6. Mean diurnal variation of mixing ratio, δ13C and δ18O of ecosystem CO2 during winter, spring and summer at different heights of the forests (n = 122-184, ± s.e.).Fig. 7. Mean diurnal variation of respiration rate, δ13C and δ18O of CO2 released from total and heterotrophic soil respiration during spring and summer (n = 122, ± s.e.).

English

Diurnal and seasonal variation of δ¹³C and δ¹⁸O of carbon dioxide in a Norway spruce forest measured with a tunable diode laser absorption spectrometer

IMK-IFU Garmisch-PartenkirchenDr. Nicolas Brüggemann | IMK-IFU | XX.YY.ZZZZKIT – a Cooperation betweenKarlsruhe Research Centerand University of KarlsruheDiurnal and Seasonal Variation of 13C and  18O of Carbon Dioxide in a Norway Spruce Forest Measured with a Tunable Diode Laser Absorption SpectrometerNicolas Brüggemann, Hans Papen, Dominik Steigner,Klaus Butterbach-BahlKarlsruhe Research CentreInstitute for Meteorology and Climate ResearchAtmospheric Environmental Research (IMK-IFU)Garmisch-PartenkirchenGermanyIMK-IFU Garmisch-PartenkirchenDr. Nicolas Brüggemann | IMK-IFU | XX.YY.ZZZZKIT – a Cooperation betweenKarlsruhe Research Centerand University of KarlsruheChallengeLitterMineralizationCO2AutotrophicrespirationAutotrophicrespirationHeterototrophicrespirationPhotosynthesisRefixation¾Disentanglingecosystem CO2component fluxes¾Understandingshort-termdynamics of CO2exchange betweenecosystem and atmosphere¾Understanding C fluxes into, withinand out of ecosystemIMK-IFU Garmisch-PartenkirchenDr. Nicolas Brüggemann | IMK-IFU | XX.YY.ZZZZKIT – a Cooperation betweenKarlsruhe Research Centerand University of KarlsruheYakir & Sternberg (2000), Oecologia 123, 297–311Major steps involved in the 18O isotopic exchangeof CO2 between a C3 leaf and the atmosphereThermodynamic equilibrationH216O + C18O16O ↔H218O + C16O16Ocatalyzed by carbonic anhydraseAs soil water and leaf water havesignificantly different 18O/16O ratios, a differentiationbetween plant and soil CO2 fluxes ispossibleIMK-IFU Garmisch-PartenkirchenDr. Nicolas Brüggemann | IMK-IFU | XX.YY.ZZZZKIT – a Cooperation betweenKarlsruhe Research Centerand University of KarlsruheTDL instrument: TGA100A (Campbell Scientific, USA)IMK-IFU Garmisch-PartenkirchenDr. Nicolas Brüggemann | IMK-IFU | XX.YY.ZZZZKIT – a Cooperation betweenKarlsruhe Research Centerand University of KarlsruheInstrumental setup for CO2 isotope measurementsIMK-IFU Garmisch-PartenkirchenDr. Nicolas Brüggemann | IMK-IFU | XX.YY.ZZZZKIT – a Cooperation betweenKarlsruhe Research Centerand University of KarlsruheCO2 profiles soil respirationIsotope-specific measurements of IMK-IFU Garmisch-PartenkirchenDr. Nicolas Brüggemann | IMK-IFU | XX.YY.ZZZZKIT – a Cooperation betweenKarlsruhe Research Centerand University of Karlsruhedate1.12.07 1.1.08 1.2.08 1.3.08 1.4.08 1.5.08 1.6.08 1.7.08 1.8.08 1.9.08 1.10.08 1.11.08 1.12.08δ18O [‰ vs. V-PDB]810121416810121416δ13C [‰ vs. PDB]-14-12-10-8-6-14-12-10-8-6CO2 [ppm]3603804004204404604803603804004204404604802m 8m 15m 50m precipitation [mm]0102030temperature [°C]-1001020wind speed [m s-1]02468precipitationair temperature (2 m) wind speed 50 mglobal radiation [W m-2]0100200300400relative humidity [%]405060708090100Global radiationrelative air humiditySeasonal courses of meteorological params and ecosystem CO2, δ13C & δ18OIMK-IFU Garmisch-PartenkirchenDr. Nicolas Brüggemann | IMK-IFU | XX.YY.ZZZZKIT – a Cooperation betweenKarlsruhe Research Centerand University of Karlsruhetime of day [CET]0 3 6 9 12 15 18 21 24δ18O [‰ vs. V-PDB]121314152m 8m 15m 50m δ13C [‰ vs. PDB]-11-10-9-8-72m 8m 15m 50m CO2 [ppm]3603804004204404602m 8m 15m 50m time of day [CET]0 3 6 9 12 15 18 21 24Dec-Feb Mar-May Jun-Augtime of day [CET]0 3 6 9 12 15 18 21 24time of day [CET]0 3 6 9 12 15 18 21 24Sep-NovSeasonal variability of diurnal cycles of ecosystem CO2, δ13C & δ18OIMK-IFU Garmisch-PartenkirchenDr. Nicolas Brüggemann | IMK-IFU | XX.YY.ZZZZKIT – a Cooperation betweenKarlsruhe Research Centerand University of Karlsruhedate1.4.08 1.5.08 1.6.08 1.7.08 1.8.08 1.9.08 1.10.08δ18O [‰ vs. V-PDB]-25-20-15-10-505-25-20-15-10-505total soil respirationheterotrophic soil respirationδ13C [‰ vs. PDB]-32-30-28-26-24-32-30-28-26-24total soil respirationheterotrophic soil respirationrespiration rate[µmol CO2 m-2 s-1]012345012345total soil respirationheterotrophic soil respirationprecipitation [mm]0102030temperature [°C]0510152025precipitationair temperature (2 m) soil temp OLsoil temp 5 cm global radiation [W m-2]0100200300400relative humidity [%]405060708090100Global radiationjulian day vs rh_2m Seasonal courses of meteorological params and soil CO2, δ13C & δ18OIMK-IFU Garmisch-PartenkirchenDr. Nicolas Brüggemann | IMK-IFU | XX.YY.ZZZZKIT – a Cooperation betweenKarlsruhe Research Centerand University of Karlsruhetime of day (CET)0 3 6 9 12 15 18 21 24-8-6-4-202total soil respirationheterotrophic soil respirationδ13C [‰ vs. PDB]-32-30-28-26total soil respirationheterotrophic soil respirationrespiration rate [µmol m-2 s-1]1.01.52.02.53.03.54.0total soil respirationheterotrophic soil respirationδ18O [‰ vs. V-PDB]Apr-May Jun-Augtime of day (CET)0 3 6 9 12 15 18 21 24time of day (CET)0 3 6 9 12 15 18 21 24SepSeasonal variability of diurnal cycles of soil CO2, δ13C & δ18OIMK-IFU Garmisch-PartenkirchenDr. Nicolas Brüggemann | IMK-IFU | XX.YY.ZZZZKIT – a Cooperation betweenKarlsruhe Research Centerand University of Karlsruhe-10.5-10.0-9.5-9.0-8.5-8.0-7.5-505101520050100150200250δ13C [‰ vs. PDB]air temp 2 m [°C]global radiation [W m -2]-10.5 -10.0 -9.5 -9.0 -8.5 -8.0 -7.5 111213141516-505101520050100150200250δ18O [‰ vs. V-PDB]air temp 2 m [°C]global radiation [W m-2]11 12 13 14 15 16 Dependency of δ13C & δ18O of ecosystem CO2 on air temperature & global radiationIMK-IFU Garmisch-PartenkirchenDr. Nicolas Brüggemann | IMK-IFU | XX.YY.ZZZZKIT – a Cooperation betweenKarlsruhe Research Centerand University of Karlsruhe-30-29-28-27510152050100150200250300δ13C [‰ vs. PDB]air temp 2 m [°C]global radiation [W m -2]total soil respirationdel13C-30 -29 -28 -27 -30-29-28-27510152050100150200250300δ13C [‰ vs. PDB]air temp 2 m [°C]global radiation [W m -2]heterotrophic soil respirationdel13C-30 -29 -28 -27 -10-8-6-4-2024510152050100150200250δ18O [‰ vs. SMOW]air temp 2 m [°C]global radiation [W m -2]total soil respirationdel18O-10 -8 -6 -4 -2 0 2 4 -10-8-6-4-2024510152050100150200250δ18O [‰ vs. SMOW]air temp 2 m [°C]global radiation [W m -2]heterotrophic soil respirationdel18O-10 -8 -6 -4 -2 0 2 4 Dependency of δ13C & δ18O of total and heterotrophic soil respiration on airtemperature & global radiationIMK-IFU Garmisch-PartenkirchenDr. Nicolas Brüggemann | IMK-IFU | XX.YY.ZZZZKIT – a Cooperation betweenKarlsruhe Research Centerand University of KarlsruheConclusions• Isotope-specific laser absorption spectroscopy is an extremelypowerful tool for long-term monitoring of C and O isotope ratios of CO2with high time resolution• There are significant seasonal differences in δ13C and δ18O of ecosystem CO2, with the highest values in summer at high temperatures and high light intensities• There is a significant differences not only in the magnitude, but also in C and O isotope ratios of soil respired CO2

Diurnal and seasonal variation of ¹³C and ¹⁸O of carbon dioxide in a Norway spruce forest measured with a tunable diode laser absorption spectrometer

https://publikationen.bibliothek.kit.edu/230075304/3815449

Diurnal and seasonal variation of ¹³C and ¹⁸O of carbon dioxide in a Norway spruce forest measured with a tunable diode laser absorption spectrometer

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