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Trennung der Komponenten des CO2 Gaswechsels von Pflanzenbeständen im Licht

Photosynthese und Respiration - die zwei dominierenden Komponenten des C-Haushaltes von Pflanzen und Ökosystemen - lassen sich mit konventionellen Methoden der Gaswechselmessung nicht mit befriedigender Präzision trennen. Dieser Sachverhalt begründet Defizite im Verständnis des C- und Energiehaushaltes von Kulturpflanzen und Ökosystemen. Im vorliegenden Vorhaben sollen neuartige CO2 Gaswechselmesstechniken in Kombination mit der kontinuierlichen Messung der C- und O-isotopischen Signaturen (d13C und d18O) des CO2 eingesetzt werden, um Photosynthese und Respiration eines Pflanzenbestandes im Licht zu quantifizieren und zu trennen. Grundlage hierfür ist die Bestimmung der natürlich entstehenden Unterschiede in der C- und O-isotopischen Signatur von photosynthetischen und respiratorischen CO2-Flüssen. Diese Ergebnisse werden mit Schätzwerten aus Untersuchungen mit anderen Methoden verglichen. In den Experimenten sollen Photosynthese, Respiration, Wachstum und Assimilateverteilung der Bestände durch differenzielle N-Ernährung manipuliert und deren Auswirkung auf die 13C- und 18O-Signaturen des respirierten und fixierten CO2 charakterisiert werden. Mit den gewonnenen Daten lässt sich erstmalig die Übertragbarkeit der bislang nur auf der Skala von Blättern verifizierten Modelle zur C- und O-Isotopendiskriminierung auf die Skala von Pflanzenbeständen und Ökosystemen überprüfen.

Water isotope values from northeastern German lake systems 2020 et seq

Water isotopes (δ2H and δ18O) were analyzed in samples collected in lakes associated to major riverine systems in northeastern Germany throughout 2020. The dataset is derived from water samples taken at a) lake shores (sampled in March and July 2020); b) buoys temporarily installed in deep parts of the lake (sampled monthly from March to October 2020); c) multiple spatially distributed spots in four selected lakes (in September 2020); d) the outflow of Müggelsee (sampled biweekly from March 2020 to January 2021). At shores, water was sampled with a pipette from 40-60 cm below water surface and directly transferred into a measurement vial, while at buoys a Limnos water sampler was used to obtain samples from 1 m below surface. Isotope analysis was conducted at IGB Berlin, using a Picarro L2130-i cavity ring-down spectrometer. The data give information about the seasonal isotope amplitude in the sampled lakes and about spatial isotope variability in different branches of the associated riverine systems.

Biomarker indices and concentrations and biomarker-based temperature estimates from the Iberian Margin core MD95-2042, composite Greenland atmospheric temperature record, and Antarctic stacks

Core MD95-2042 alkenone and GDGT data: This dataset provides the following information for core MD95-2042: depth, age, summed OH-GDGT, iGDGT, and di-unsaturated and tri-unsaturated C37 alkenone concentrations, OH-GDGT-based, iGDGT-based, and alkenone-based paleothermometric indices, GDGT-2/GDGT-3 ratio, and biomarker-based sea surface temperature (SST) and 0‐ to 200‐m sea temperature (subT; gamma function probability distribution for target temperatures with a = 4.5 and b = 15) estimates. Sediment samples were taken every 5 cm from core MD95-2042 and homogenized before lipid extraction. The lipid extracts were splitted into two fractions: one for alkenone analysis by gas chromatography coupled to a flame ionization detector, and the other for GDGT analysis by high-performance liquid chromatography coupled to mass spectrometry. All GDGT analyses were done in duplicate. The 1σ analytical uncertainties from 37 replicate analyses of the core catcher sample from core MD95-2042 are 0.007 (0.4 °C) for RI-OH, 0.008 (0.2 °C) for RI-OH′, 0.003 (0.2 °C) for TEX86, 0.238 for GDGT-2/GDGT-3, and 0.010 (0.26 °C) for UK′37. RI-OH′-SST estimates are from the following global calibration: SST = (RI-OH′ + 0.029)/0.0422 (Fietz et al., 2020). RI-OH-SST estimates are from the following global calibration: SST = (RI-OH − 1.11)/0.018 (Lü et al., 2015). TEX86H-SST estimates are from the following regional paleocalibration: SST = 68.4 × TEX86H + 33.0 (Darfeuil et al., 2016). UK′37-SST estimates are from the following global calibration: SST = 29.876 × UK′37 − 1.334 (Conte et al., 2006). Bayesian calibrations were also used for TEX86-SST and TEX86-subT estimates (BAYSPAR; Tierney & Tingley, 2014, 2015) and for UK′37-SST estimates (BAYSPLINE; Tierney & Tingley, 2018). Alkenone data covering the 160–70 and 70–0 ka BP periods are from Davtian et al. (2021) and Darfeuil et al. (2016), respectively. GDGT data covering the 160–45 ka BP period are from Davtian et al. (2021). The age model of core MD95-2042 for the 160–43 and 43–0 ka BP periods was obtained by tuning to Chinese speleothems (Cheng et al., 2016) and by recalibrating existing 14C ages with the Marine20 calibration curve (Heaton et al., 2020), respectively. MIS, Marine Isotope Stage; GDGT, glycerol dialkyl glycerol tetraether; and N/A, not available. Greenland atmospheric temperature record: This dataset consists in a composite Greenland atmospheric temperature record, which was built with the following records: the GISP2 atmospheric temperature record by Kobashi et al. (2017) for the 10–0 ka BP period, the NGRIP atmospheric temperature record by Kindler et al. (2014) for the 120–10 ka BP period, and the NEEM atmospheric temperature record by NEEM community members (2013) for the 129–120 ka BP period. The NEEM temperature anomalies obtained by NEEM community members (2013) were shifted by –31 °C to obtain absolute air temperatures. The employed age model is the one of Davtian and Bard (2023) for Greenland and Antarctic ice-core records. Antarctic δ18Oice and atmospheric temperature stacks: This dataset consists in two stacks of three Antarctic records (EDC, EDML, and WD), one for δ18Oice and the other for atmospheric temperature: both stacks are provided with their stacking uncertainties. To build the Antarctic δ18Oice stack, the Antarctic δ18Oice records were resampled every 10 years before centering to zero means and normalization to unit standard deviations over the 140–0 ka BP period (68–0 ka BP for WD). To optimize the continuity between the portions with and without the WD ice core, the Antarctic δ18Oice records were centered to zero means over the 68–67 ka BP period. The resulting Antarctic δ18Oice records were then averaged and stacking uncertainties were calculated as the pooled standard deviation of the stacked Antarctic δ18Oice records divided by the square root of the number of stacked Antarctic δ18Oice records. The final Antarctic δ18Oice stack, expressed in ‰, has the same standard deviation as the δ18Oice record from EDML over the 140–0 ka BP period, and has a zero mean over the 1–0 ka BP. The Antarctic atmospheric temperature stack was built like the Antarctic δ18Oice stack, except that the Antarctic δ18Oice records were corrected for seawater δ18Oice variations before conversion into atmospheric temperature. The employed age model is the one of Davtian and Bard (2023) for Greenland and Antarctic ice-core records.

Long-term averages of mean annual temperatures (MAT), the respective summer (July/August) and winter (Dec/Jan) temperatures and δ18Oprecipitation values of 84 European sites (GNIP, IAEA/WMO, 2023)

The dataset contains long‐term means of δ18Oprecipitation values and temperatures from 84 European sites (GNIP database; IAEA/WMO, 2023), which were used to estimate mean annual (palaeo-) temperatures from the measured oxygen isotope data on horse tooth enamel phosphate. Mean temperatures of the warmest (July/August) and coldest (December/January) periods were considered representative for summer and winter temperatures, respectively, using the peak and trough values of the modelled phosphate data for their calculation.

Water isotope values and chemical parameters in time series samples (March 2020 - January 2021) from Müggelsee, Germany

Water isotopes (δ2H and δ18O) were analyzed in samples collected in lakes associated to major riverine systems in northeastern Germany throughout 2020. This sub-dataset is derived from water samples taken before the outflow of Müggelsee. Sampling was conducted biweekly from March 2020 to January 2021. Samples were taken with a pipette from 40-60 cm below water surface and directly transferred into a measurement vial. Isotope analysis was conducted at IGB Berlin, using a Picarro L2130-i cavity ring-down spectrometer. Water chemical and physical parameters are daily average values derived from the Müggelsee long-term data monitoring station (https://emon.igb-berlin.de/grosser_mueggelsee.html). The data give information about the seasonal isotope amplitude at Müggelsee over the studied time period.

Water isotope values in time series samples (March - October 2020) collected at buoys deployed in northeastern German lake systems

Water isotopes (δ2H and δ18O) were analyzed in samples collected in lakes associated to major riverine systems in northeastern Germany throughout 2020. This sub-dataset is derived from water samples taken at buoys temporarily installed in deep parts of the lake. Samples were taken monthly to bimonthly from March to October 2020. A Limnos water sampler was used to obtain samples from 1 m below water surface. Isotope analysis was conducted at IGB Berlin, using a Picarro L2130-i cavity ring-down spectrometer. Water temperatures were measured in similar depths with an Aqua TROLL 600 multiparameter sonde (In-Situ, Fort Collins, CO, USA). The data give information about the seasonal isotope amplitude in the sampled lakes and about spatial isotope variability in different branches of the associated riverine systems.

Water isotope values from a spatial campaign conducted in four northeastern German lakes in September 2020

Water isotopes (δ2H and δ18O) were analyzed in samples collected in lakes associated to major riverine systems in northeastern Germany throughout 2020. This sub-dataset is derived from water samples taken at multiple spatially distributed spots in four selected lakes. A Limnos water sampler was used to obtain samples from 1 m below water surface on 29th and 30th September 2020. Isotope analysis was conducted at IGB Berlin, using a Picarro L2130-i cavity ring-down spectrometer.

Water isotope values in shore samples collected in March and July 2020 from northeastern German lake systems

Water isotopes (δ2H and δ18O) were analyzed in samples collected in lakes associated to major riverine systems in northeastern Germany throughout 2020. This sub-dataset is derived from water samples collected from lake shores. Samples were taken in March and July 2020 with a pipette from 40-60 cm depth below water surface and directly transferred into a measurement vial. Stable isotope analysis was conducted at IGB Berlin, using a Picarro L2130-i cavity ring-down spectrometer. The data give information about the seasonal isotope amplitude in the sampled lakes and about spatial isotope variability in different branches of the associated riverine systems.

Oceanic surface water isotopic compositions calibrated data from POLARSTERN cruise PS102

Isotopic measurements of seawater sampled on-board Polarstern research vessel

Water isotope time series (March 2020 - March 2021) of samples collected at A. P. Møller Skolen, Kleine Breite, Schlei

Time series of stable isotopes (δ2H and δ18O) were analyzed in water samples collected near the A. P. Møller Skolen, Schleswig (Kleine Breite, Schlei), in biweekly to monthly intervals between March 2020 and March 2021. Water was sampled with a pipette from ca. 0.5 m below water surface and directly transferred into a measurement vial. Isotope analysis was conducted at IGB Berlin, using a Picarro L2130-i cavity ring-down spectrometer. Water chemical parameters were measured in-situ with a modular WTW 3440 multiparameter devices and regularly calibrated conductivity cells (MPP 930 IDS, TetraCon® 925-P). The data give information about the seasonal isotope amplitude at the sampled locations and about spatial variability along the transects.

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