BG2.3 | Oxygen and hydrogen isotope analyses of aquatic and terrestrial compounds: Advances in methods, models, and interpretation
Oxygen and hydrogen isotope analyses of aquatic and terrestrial compounds: Advances in methods, models, and interpretation
Convener: Marco Lehmann | Co-conveners: Marc-Andre CormierECSECS, Meisha Holloway-Phillips
| Thu, 27 Apr, 16:15–18:00 (CEST)
Room 2.95
Posters on site
| Attendance Thu, 27 Apr, 10:45–12:30 (CEST)
Hall A
Posters virtual
| Attendance Thu, 27 Apr, 10:45–12:30 (CEST)
vHall BG
Orals |
Thu, 16:15
Thu, 10:45
Thu, 10:45
This session aims to bring together scientists from different fields applying single and dual oxygen and hydrogen isotope approaches on environmental-derived compounds for the reconstruction of climatic and biological processes that go beyond standard isotope analyses of water. We invite researchers working on different compounds (e.g. lipids, (hemi-) cellulose, non-structural carbohydrates) from aquatic (e.g., fish, microbes and seaweed) and terrestrial (e.g., grasses, mosses and trees) origins across all spatiotemporal scales and archives (e.g. herbarium, peat, sediments, loess and tree rings). We also encourage people working with all techniques (IRMS-, NMR- or spectroscopy-based) to present advances in methods, as well as researchers focusing on improving oxygen and hydrogen isotope-based models to discuss their approaches. In summary, the session will offer an overview on oxygen and hydrogen applications across different ecosystems in order to facilitate the interpretation of compound-specific isotope patterns.

Orals: Thu, 27 Apr | Room 2.95

Chairpersons: Marco Lehmann, Marc-Andre Cormier, Meisha Holloway-Phillips
On-site presentation
Michael Zech, Johannes Hepp, Mario Tuthorn, Bruk Lemma, Lucas Bittner, Roland Zech, Kazimierz Rozanski, and Bruno Glaser

The oxygen and hydrogen isotopic composition δ2H and δ18O of leaf and lake water reflects the isotopic composition of source water/precipitation modified by evapo(transpi)rative enrichment. This later enrichment can be illustrated and quantified using δ2H- δ18O diagrams and the deuterium-excess. The enrichment of leaf water thereby depends primarily on relative air humidity (RH) and can be investigated using biomarkers being produced in leaves. The enrichment of lake water depends on lake evaporation and can be investigated using biomarkers being produced by aquatic macrophytes or algae. Provided that unambiguous terrestrial and aquatic biomarkers can be identified in lake sediments, the coupling of δ2H and δ18O hence allows reconstructing RH (paleohygrometry approach) and lake evaporation history. In our contribution, we discuss the potential, the advances and the limitation of the coupled isotope approach based on leaf wax-derived n-alkane and hemicellulose-derived sugar biomarkers (δ2Hn-alkanes-  δ18Osugars).



Hepp, J., Mayr, C., Rozanski, K., Schäfer, I., Tuthorn, M., Glaser, B., Juchelka, D., Stichler, W., Zech, R. and Zech, M., 2021. Validation of a coupled δ2Hn-alkane18Osugar paleohygrometer approach based on a climate chamber experiment. Biogeosciences 18, 5363-5380.

Hepp, J., Wüthrich, L., Bromm, T., Bliedtner, M., Schäfer, I. K., Glaser, B., Rozanski, K., Sirocko, F., Zech, R., and Zech, M., 2019. How dry was the Younger Dryas? Evidence from a coupled δ2H-δ18O biomarker paleohygrometer applied to the Lake Gemündener Maar sediments, Western Eifel, Germany, Climate of the Past 15, 713-733.

Zech, M., Tuthorn, M., Detsch, F., Rozanski, K., Zech, R., Zöller, L., Zech, W. and Glaser, B., 2013. A 220 ka terrestrial δ18O and deuterium excess biomarker record from an eolian permafrost paleosol sequence, NE-Siberia. Chemical Geology 360-361, 220-230.

How to cite: Zech, M., Hepp, J., Tuthorn, M., Lemma, B., Bittner, L., Zech, R., Rozanski, K., and Glaser, B.: Paleohygrometry and reconstruction of lake evaporation history based on compound-specific hydrogen and oxygen isotope analyses of biomarkers – principle of the coupled isotope approach, advances and limitations, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16430,, 2023.

On-site presentation
Anna Wieland, Markus Greule, Philipp Roemer, Jan Esper, Nemiah Ladd, Marco Lehmann, Philipp Schuler, and Frank Keppler

Stable hydrogen isotope values of tree-lignin methoxy groups (δ2HLM) are increasingly applied to reconstruct the stable hydrogen isotope composition of precipitation (δ2Hprecip) and mean annual temperatures in mid-latitude regions. The climate reconstructions are typically derived considering an isotope fractionation from -200 mUr to -216 mUr between lignin methoxy groups and tree source water (Keppler et al. 2007, Anhäuser et al. 2017, Greule et al., 2021, Porter et al. 2022, Wieland et al. 2022). This empirical relationship was derived from different tree species collected along a European north-south transect at elevations below 1000 m above sea level. However, it is so far unknown how environmental and physiological factors such as tree age, tree species, salinity, elevation, or precipitation amount influence the biochemical hydrogen isotope fractionation between lignin methoxy groups and precipitation.

We here present several recent investigations that show how environmental and tree physiological factors might influence δ2HLM values. For example, potential amount effects of precipitation are analysed using tree cores from the Carpathians, where the mountain barrier led to large precipitation events at the Luv site. In addition, potential age trends are studied using trees from Greece that are over 500 years old, and the phylogenetical range of δ2HLM values is assessed by comparing 70 different tree species grown under uniform climatic conditions. Finally, the influence of salinity is evaluated by analysing different mangrove tree species from Australia.

The improvements and limitations of δ2HLM values as a climate proxy at different spatial and temporal scales will be discussed. In order to better reconstruct long-term climate variations, additional gain is expected from the cross-comparison of multiple isotope proxies, including stable carbon isotope values of cellulose and lignin methoxy groups, as well as stable oxygen isotopes of cellulose.


Anhäuser, T., Greule, M., Polag, D., Bowen, G. J., and Keppler, F.: Mean annual temperatures of mid-latitude regions derived from δ2H values of wood lignin methoxyl groups and its implications for paleoclimate studies, Sci. Total Environ., 574, 1276–1282,, 2017.

Greule, M., Wieland, A., and Keppler, F.: Measurements and applications of δ2H values of wood lignin methoxy groups for paleoclimatic studies, Quaternary Sci. Rev., 268, 107107,, 2021.

Keppler, F., Harper, D. B., Kalin, R. M., Meier-Augenstein, W., Farmer, N., Davis, S., Schmidt, H. L., Brown, D. M., and Hamilton, J. T. G.: Stable hydrogen isotope ratios of lignin methoxyl groups as a paleoclimate proxy and constraint of the geographical origin of wood, New Phytol., 176, 600–609,, 2007.

Porter, T. J., Anhäuser, T., Halfar, J., Keppler, F., Csank, A. Z., and Williams, C. J.: Canadian Arctic Neogene temperatures reconstructed from hydrogen isotopes of lignin‐methoxy groups from sub‐fossil wood, Paleoceanogr. Paleoclimatology, 37,, 2022.

Wieland, A., Greule, M., Roemer, P., Esper, J., and Keppler, F.: Climate signals in stable carbon and hydrogen isotopes of lignin methoxy groups from southern German beech trees, Clim. Past, 18, 1849–1866,, 2022.

How to cite: Wieland, A., Greule, M., Roemer, P., Esper, J., Ladd, N., Lehmann, M., Schuler, P., and Keppler, F.: Recent progress in the application of hydrogen isotopes from tree-ring lignin methoxy groups as a climate proxy, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6301,, 2023.

On-site presentation
Daniel B. Nelson, Jochem Baan, Meisha Holloway-Phillips, and Ansgar Kahmen

Plant organic compounds such as cellulose or n-alkanes are often utilized as recorders of oxygen (δ18O) or hydrogen (δ2H) isotopic signals to inform on past climate or environmental conditions, or on plant physiological changes. This is because these compounds can persist in the geologic record for decades to millennia or longer in select cases. Yet, large differences have often been observed among plant organic compound δ2H or δ18O values for species growing in a single location due to the balance between variable leaf water isotopic enrichment and variable biochemical isotopic effects among species. Distinguishing between these sources of variability and making use of these signals is an ongoing challenge, in part because of the limited number of studies that have explored the extent to which the different drivers influence the isotopic composition of each compound class and element within a single location.

We present a detailed assessment of isotopic variation in relevant plant water pools and cellulose δ2H and δ18O values, in combination with n-alkane δ2H values in 192 eudicot species grown in a botanical garden in a single growing season, as well as year-to-year comparisons for consecutive years (2019-2020). Our results show that variation in leaf water δ2H values were not a strong driver for the observed variation in organic compound δ2H values across eudicot species. Additionally, while correlation between δ2H and δ18O values found in plant source water and leaf water was transferred to cellulose, the explanatory power of this correlation was strongly diminished. This indicates that additional biochemical isotope fractionation caused substantial variation in organic compound δ2H and/or δ18O values across species. Moreover, variation in cellulose δ2H values were poorly correlated with δ2H values from n-alkanes, suggesting that the biochemical pathways associated with different compounds were accompanied by varying isotope effects. Lastly, cellulose δ2H and δ18O values changed more than n-alkane δ2H values from one year to the next. This implies that, cellulose δ2H and δ18O values are more sensitive to environmental differences between growing seasons compared to δ2H values from n-alkanes, and thus that the environmental forcing effects on isotope values are not equal between compounds. Overall, we found that variation in organic compound δ2H, and possibly also δ18O, values across species and between growing seasons was substantially more strongly driven by biochemical isotope fractionation than by isotope values of plant water. Therefore, to the extent that it is possible, biochemical responses to environmental changes should be considered in interpretations of organic compound δ2H and δ18O values to reconstruct the past. Furthermore, there is potential to recover plant responses to environmental changes from plant organic compound δ2H and/or δ18O values when the measurements are incorporated into multi-compound or multi-proxy paleoenvironmental and paleophysiological inquiries.

How to cite: Nelson, D. B., Baan, J., Holloway-Phillips, M., and Kahmen, A.: Biochemically driven isotope effects differ for n-alkane hydrogen and for cellulose hydrogen and oxygen among eudicot plant species and between years, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15357,, 2023.

Virtual presentation
Takeshi Nakatsuka, Minori Kato, Yoshikazu Kato, and Zhen Li

In contrast to tree-ring width, oxygen isotope ratio (δ18O) of tree-ring cellulose does not usually show clear age trend, indicating that it can be utilized to reconstruct past climate variation not only for the high frequency domain but also for the low frequency domain. However, in some conifer trees growing in dense forests, there are predominant trends in the tree-ring cellulose δ18O decreasing with age as well as the tree-ring width, making the long-term climate reconstruction difficult. In such trees, hydrogen isotope ratios (δ2H) of tree-ring cellulose usually show the opposite trend to that of δ18O, suggesting that the age trend in tree-ring δ18O and δ2H are owing to age-related changes in the rate of post-photosynthetic isotope exchanges between carbohydrate and xylem water before the cellulose synthesis.

Based on an assumption that tree-ring cellulose δ18O and δ2H vary in positive and negative relationships due to climatological and physiological factors respectively, Nakatsuka et al (2020) proposed a simple method to separate climatological and physiological components in original tree-ring cellulose δ18O time-series by integrating the δ18O and δ2H data in order to reconstruct past climate variation for all frequency domains seamlessly. In this method, it is very important to fix the quantitative relationship between the long-term age-related changes in δ18O and δ2H due to the post-photosynthetic process. However, it is quite difficult to elucidate the physiological relationship between δ18O and δ2H quantitatively by investigating the tree-ring δ18O and δ2H time-series solely because they are influenced not only by the physiological mechanism but also by climate variations.

Here, we propose a new strategy to study physiological controls on the tree-ring cellulose δ18O and δ2H quantitatively. It is based on vertical changes in tree-ring isotope ratios along trunks, those have been seldom investigated in previous dendrochronological studies. We measured inter-annual variations in tree-ring cellulose δ18O and δ2H at different heights in individual trunks of cypress (Chamaecyparis obtusa) and cedar (Cryptomeria japonica) in central Japan and found that the cellulose isotope ratios showed clear vertical trends together with the ring width. From top to bottom along the trunk, the δ18O decreased and the δ2H increased, suggesting that we can monitor the age trend in tree rings not only in the horizontal direction but also in the vertical direction, such that “the top is youngest and the bottom is oldest”, without being influenced by the climate variation. Based on the fact that leaves are located only at the top of trunk in the dense conifer forest, we will discuss the effects of post-photosynthetic isotopic exchanges quantitatively and elucidate the mechanism underlying the apparent age trends in the tree-ring cellulose δ18O and δ2H.

How to cite: Nakatsuka, T., Kato, M., Kato, Y., and Li, Z.: Vertical changes in cellulose oxygen and hydrogen isotope ratios along conifer trunks: Implications for physiological controls on tree-ring isotopes, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10378,, 2023.

Virtual presentation
Xin Song

Stable oxygen isotope composition of tree ring cellulose (d18Ocell) has been increasingly used as a tool for reconstruction of environmental conditions (e.g. air temperature, precipitation, relative humidity) and ecophysiological variables (e.g. leaf temperature, stomatal conductance) that prevail during the period of tree growth. The current tree-ring d18Ocell mechanistic model assumes no oxygen exchange/biochemical fractionation effect during sucrose loading from the source leaf to the phloem, but is has been debated as to whether or not such an assumption is valid. Here, we performed an experimental study to quantify the possible extent of carbonyl-water exchange of oxygen during phloem loading. Towards this goal, we used a custom-made multiple-channel water vapor isotope signal labeling system to expose experimental plants to a range of water vapor d18O compositions under physiologically stable conditions; this in turn allowed the creation of a large gradient in d18O of leaf water, leaf sucrose, and phloem sucrose without disrupting plant physiology. We will present data collected from this experiment to examine the d18O relationships among the various water and sucrose pools, which may provide some insights into the possible isotope effects associated with sucrose translocation from leaf to the phloem. 

How to cite: Song, X.: Does carbonly-water exchange of oxygen occur during phloem loading of sucrose? An exploratory study involving vapor 18O labelling techniques.    , EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4036,, 2023.

On-site presentation
Akira Kagawa

Where do oxygen and hydrogen atoms of organic matter from terrestrial plant, such as O and H in cellulose, come from? We already know that O in cellulose originates from water within plants, instead of CO2 taken in via leaf stomata, and stable isotope tracers gave an answer to this question (Deniro & Epstein 1979, Science).

 We know that all vascular plants acquire water from the soil via their roots. However, in recent years, we have learned that plants can also acquire significant amount of water directly through their leaves (Burgess and Dawson 2004, Plant, Cell & Environment; and others) and foliar-absorbed water can be a source of oxygen atoms of sugars in leaves (Lehmann et al. 2018, New Phytologist). Then, an interesting question comes up to our mind: where does the water that eventually become O and H in cellulose come from? Until recently, these water sources were thought to only be taken up by roots, as we have learned from our introductory biology textbook (Dawson 2022, Tree Physiology). However, validity of this common perception has recently been questioned, when, using hydrogen and oxygen isotope tracer in vapour or mist form, two researchers have demonstrated that foliar-absorbed water can be assimilated into organic matter (Studer et al. 2015, Biogeosciences; Lehmann et al. 2018). However, relative contributions of foliar-absorbed water and root-absorbed water assimilation into O and H in cellulose have remained an open question.

I therefore devised a labelling method that utilizes two different water sources, one enriched in deuterium and one enriched in oxygen-18, to simultaneously label both foliar-absorbed and root-absorbed water and quantify their relative contributions to plant organic matter (Kagawa 2022, Tree Physiology, Using this new method, I will present evidence that, in the case of well-watered Cryptomeria japonica, hydrogen and oxygen incorporated into new leaf cellulose in the rainy season derives mostly from foliar-absorbed water (69% from foliar-absorbed water and 31% from root-absorbed water), while that of new root cellulose derives mostly from root-absorbed water (20% from foliar-absorbed water and 80% from root-absorbed water), and new branch xylem is somewhere in between (55% from foliar-absorbed water and 45% from root-absorbed water, see figure below). The novel dual labelling method first implemented in this study enables separate and simultaneous labelling of foliar-absorbed and root-absorbed water, and offers a new tool to study the uptake, transport, and assimilation processes of these waters in terrestrial plants. Thanks to our recent methodological breakthroughs, this new tool will soon be publicly available, as it has become easy to enclose wet tissue samples from labelled trees into smooth wall tin capsules without significant leaks, and our laboratory can now routinely analyze H and O isotope ratios of 200 samples that are labelled with heavy water per week.


How to cite: Kagawa, A.: Foliar water uptake as a source of hydrogen and oxygen in cellulose of vascular plants, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1769,, 2023.

On-site presentation
Nemiah Ladd, Antonia Klatt, Cindy de Jonge, Marta Reyes, Carsten Schubert, and Daniel Nelson

Hydrogen isotope fractionation between source water and lipids is highly variable among different taxonomic groups, and also among different compound classes within individual organisms. This variability results in lipid δ2H values that often span as much as two orders of magnitude more variability than that of environmental waters within typical ecosystems, indicating that lipid δ2H values may provide valuable biochemical and ecological information. These applications of lipid δ2H values remain underexplored.

Recent results from algal batch cultures indicate that hydrogen isotope fractionation by cyanobacteria differs significantly compared to eukaryotic algae. In particular, in single species cultures with constant water δ2H values, cyanobacteria tend to produce fatty acids that are slightly 2H-enriched compared to those from most eukaryotic algae, while phytol from cyanobacteria is very 2H-depleted compared to phytol from eukaryotes. This results in larger offsets between the δ2H values of phytol and fatty acids for cyanobacteria than those observed in eukaryotic algae. In order to determine if δ2H offsets between fatty acids and phytol change in freshwater lakes with variable abundance of cyanobacteria, we collected algal biomass from two depths in the water column of Rotsee, a small lake in central Switzerland, every second week from January 2019 to February 2020. During this time the percentage of algal biovolume from cyanobacteria ranged from 0 to 82 %, with two distinct cyanobacterial blooms occurring in July and October.

Water isotopes in the lake were relatively stable throughout the year, with water δ2H values varying by < 10 ‰. Lipid δ2H values, on the other hand, displayed extreme variability throughout the year. Palmitic acid (C 16:0) δ2H values varied by nearly 100 ‰ (–282 to –192 ‰), while those of phytol varied by more than 200 ‰ (–417 to –168 ‰). Consistent with expectations based on the results of cultures of single algal species, cyanobacterial blooms were characterized by larger offsets between the δ2H values of palmitic acid and phytol, and these offsets were positively correlated with the percentage of total algal biovolume attributable to cyanobacteria (R2 = 0.29; p < 0.01). These results suggest that hydrogen isotope offsets between palmitic acid and phytol in sediments have the potential to be developed as proxies for past cyanobacterial blooms, and demonstrate that hydrogen isotopes of lipids in the geologic record that are produced by many different types of aquatic organisms are more likely to be driven by ecological changes rather than changes in water isotopes.

How to cite: Ladd, N., Klatt, A., de Jonge, C., Reyes, M., Schubert, C., and Nelson, D.: Hydrogen isotope offsets between palmitic acid and phytol increase during cyanobacterial blooms, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7297,, 2023.

On-site presentation
Elizabeth Thomas, Allison Cluett, Owen Cowling, Devon Gorbey, Kayla Hollister, Sofia Kjellman, and Kurt Lindberg

Constraining the hydrological response to past climate change can improve climate model predictions. These constraints are most useful when provided in variables that are native to climate models (e.g., precipitation or soil water isotope values during a defined season). Leaf wax hydrogen isotopes extracted from lake sediments are valuable proxies to reconstruct the hydrological cycle. In some lakes, multiple leaf wax compounds may provide information about different aspects of the climate system (e.g., precipitation isotope seasonality, growing season evaporation, etc.), increasing the amount of information we obtain from a single measurement. Yet, the pathway by which climate signals are recorded in leaf wax hydrogen isotopes can be complex, as the isotope signal is filtered through the environment (lake or soil water) and the sensor (integrating waxes from aquatic plants and from terrestrial plants throughout the lake’s catchment). This presentation will summarize our recent and ongoing research examining how climate signals are filtered through both the environment and sensor, with the goal of providing reconstructions in terms native to isotope-enabled climate models. We will highlight studies examining lake water isotope systematics and leaf wax sources to lake sediments, emphasizing aspects of these frameworks that are applicable to other stable water isotope proxies. We will also discuss outstanding questions and avenues for future research.

How to cite: Thomas, E., Cluett, A., Cowling, O., Gorbey, D., Hollister, K., Kjellman, S., and Lindberg, K.: Terrestrial and aquatic leaf wax hydrogen isotope proxy system models: Recent advances and remaining gaps, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14386,, 2023.


Posters on site: Thu, 27 Apr, 10:45–12:30 | Hall A

Chairpersons: Marco Lehmann, Marc-Andre Cormier, Meisha Holloway-Phillips
Philipp Schuler, Oliver Rehmann, Valentina Vitali, Matthias Saurer, Nina Buchmann, Arthur Gessler, and Marco Lehmann

Recent methodological achievements in determining the non-exchangeable hydrogen isotopic composition (δ2Hne) of non-structural carbohydrates such as sugars allow to disentangle of so far hidden hydrogen isotope (2H) fractionation processes influencing δ2Hne of plant carbohydrates. We conducted two climate chamber experiments to have a closer look at the basic biochemical drivers of the photosynthetic 2H fractionation between water and sugar and the post-photosynthetic 2H fractionation between sugars and cellulose in leaves: First, we studied the impact of the different biochemical reactions in 10 species with C3, 7 species with C4, and 8 species with CAM carbon fixation pathways, and their response to changes in temperature and vapor pressure deficit (VPD). Second, we investigated the impact of a temperature increase from 10 to 40°C in 5°C steps under a constant VPD on leaf level photosynthesis and metabolic functioning of 7 plant species. The first experiment revealed distinct differences in the photosynthetic 2H fractionation between C3, C4, and CAM plants. In addition, the observed intensity and direction of the shifts in δ2Hne in response to changes in temperature and VPD in C3 plants was species specific, absent in C4 plants, and again species-specific in CAM plants. However, post-photosynthetic 2H fractionation was very similar among the three types of carbon fixation. We demonstrate that, in contrary to widespread believes, the 2H enrichment during post-photosynthetic 2H fractionation is driven by the carbohydrate metabolism, and not by an isotopic exchange with surrounding water. The results of the second experiment identified a plants’ metabolic activity, and its response to changes in temperature, as a major driver of the post-photosynthetic 2H fractionation of leaf sugars in C3 species. Our results clearly demonstrate that δ2Hne of plant carbohydrates are driven by plants metabolism and its response to the environment, which are species-specific. This will help to improve our current ability to interpret δ2Hne chronologies in tree rings and other plant archives, and to use 2H fractionation in carbohydrates as a novel proxy to study a plants’ metabolic properties.

How to cite: Schuler, P., Rehmann, O., Vitali, V., Saurer, M., Buchmann, N., Gessler, A., and Lehmann, M.: Novel insights into the biochemical drivers shaping hydrogen isotope values of sugar and cellulose within a plants’ leaf, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2967,, 2023.

Haoyu Diao, Marco M. Lehmann, Shengnan Ouyang, and Arthur Gessler

Drought-induced tree mortality is occurring more frequently in the world, with both the direct impact of drought (i.e., heat and drought events) and the mortality predisposition (e.g., tree nutrition status) influencing death or survival of trees. The oxygen and hydrogen isotopic compositions (δ18O and δ2H) of plant water are widely used as hydrological indicators. Both elements in water are tightly correlated and are the key source for the isotopic composition of plant organic matter. Yet, recent studies show that the relationship between δ18O and δ2H values in organic matter is weaker and more divergent. This is probably caused by physiological and metabolic processes (i.e., assimilation, assimilate allocation, use of reserves) that are integrated into δ2H but not into δ18O. This let us hypothesize that δ2H can function as a useful tool in tree mortality research to study assimilate and storage related reason (i.e., carbon starvation) of tree death, but more knowledge is urgently needed.

To test our hypothesis, we studied the pre-disposal fertilization and drought effects on δ18O and δ2H values in plant water and organic matter in a greenhouse experiment. We planted three years old saplings of Abies alba, Acer pseudoplatanus, Picea abies, Pinus sylvestris and Quercus petraea, half of which were treated with a slow-release formula fertilizer (control (F0) and fertilization (F+)); one year later, half of the F0 and half of the F+ plants were selected for a lethal drought treatment (control (D0) and drought (D+)), i.e., D0 plants were watered to field capacity, while D+ plants received no more water until they died. After 6 weeks of drought, leaf and twig samples were collected for δ18O and δ2H analyses of plant water. After the D+ plants died (i.e., 9-15 weeks after start of drought), additional leaf and stem material were collected from a same number of D0 and D+ plants. Organic matter of leaf and tree-ring of the recent year were prepared for δ18O and δ2H analyses. Additional physiological and metabolic factors were measured to examine the treatment effects.

Across all species, we found that the pre-disposal fertilization had no significant effect on δ18O and δ2H values of plant water and organic matter. On the other hand, the drought treatment significantly increased both δ18O and δ2H values of leaf and twig water, while it only significantly increased δ2H values of leaf and tree-ring organic matter. These results indicate that δ2H in leaf and tree-ring organic matter in dying trees can capture drought-induced tree mortality signals. We propose that the 2H-enrichment in the drought-exposed trees might be related to (i) the imprint of 2H-enriched signal of plant water; (ii) drought-induced changes in the metabolic processes of sugar biosynthesis; (iii) drought-induced changes in the use of carbon reserves. In summary, our study supports the idea that hydrogen isotopes can function as a potential diagnostic tool in tree mortality studies.

How to cite: Diao, H., Lehmann, M. M., Ouyang, S., and Gessler, A.: Hydrogen isotopes in leaf and tree-ring organic matter as potential indicators of drought-induced tree mortality, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5629,, 2023.

Marco M. Lehmann, Philipp Schuler, Leonie Schönbeck, Oliver Rehmann, Haoyu Diao, Valentina Vitali, and Charlotte Grossiord

Stable isotope compositions of carbon (δ13C) and oxygen (δ18O) in plant carbohydrates such as photosynthetic assimilates or cellulose are widely applied tools to reconstruct climate and plant physiological responses. In contrast, applications of hydrogen isotope composition (δ2H) in plant carbohydrates are limited because of previous methodological constrains and limited knowledge on processes causing hydrogen isotope fractionations. To better understand the individual climatic drivers of isotopic variations in tree rings, particularly for δ2H, we performed a controlled experiment over one growing season in climate chambers with saplings of broadleaf and conifer tree species. The growing conditions resembled conditions that can be typically found in the field: vapor pressure deficit (VPD; 1.0, 1.6, and 2.2 kPa), air temperature (T; 25 and 30 °C), and soil drought (D, well-watered and extreme dry).  After 5 months of treatment, δ13C, δ18O, and δ2H of water, sugars and starch in stems and leaves, as well as in cellulose of the recent year tree rings were measured. For δ2H analyses of plant carbohydrates, we applied a newly developed hot water vapour equilibration method (Schuler et al., 2022, Across all species, first results show that the three elements in tree-ring cellulose respond differently to the climatic drivers: both δ2H and δ13C values increased with increases in D and VPD, but the VPD responses were more pronounced under high than under low T conditions. In contrast, δ18O values were affected by T and VPD, while the VPD response was more pronounced under wet than under dry soil D conditions. Thus, the combination of δ2H and δ13C values could be used to identify D occurrences independent of VPD conditions, while δ18O value is a better indicator for T and VPD responses. In the following steps, the isotopic variations in tree-ring cellulose will be linked to those in water, sugars, and starch and their concentrations in leaf and stem material, as well as to various other structural and functional traits which have been measured throughout the experiment (Schönbeck et al., 2022, With this unique experimental design, we aim to provide new knowledge facilitating the interpretation of stable isotope patterns in tree rings under field conditions.

How to cite: Lehmann, M. M., Schuler, P., Schönbeck, L., Rehmann, O., Diao, H., Vitali, V., and Grossiord, C.: Effects of vapour pressure deficit, temperature and soil drought on triple isotope patterns of assimilates and tree-ring cellulose, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6353,, 2023.

Charlotte Angove, Marco Lehmann, Matthias Saurer, Guido Wiesenberg, Giles Young, and Katja Rinne-Garmston

It is essential to comprehensively understand past climate and tree response to climate change because trees are directly exposed to rapid, intensifying, and widespread climate change. Both tree rings and leaf n-alkanes are long-term biomarkers which can help to better understand past climate and/or tree response to climate change. For example, interpreting carbon and oxygen stable isotopes in tree rings contribute to understanding past climate and tree response to climate change. However, greater insight could be achieved if hydrogen stable isotopes can also be clearly interpreted. To clearly interpret hydrogen isotopes in tree rings it is necessary to discover which aspects of climatic variability and tree physiology are most clearly expressed by hydrogen isotopes in tree rings. Additionally, the climatic signal of hydrogen stable isotopes in leaf n-alkanes can be deposited to soil and sediments from plants, and their climatic soil record can date back to thousands to millions of years ago. However, there are still aspects of plant physiology that have not been accounted for in leaf n-alkane hydrogen isotope interpretation, which limits the reliability of their interpretation. While data from tree rings and leaf n-alkanes are rarely combined, both tree rings and leaf n-alkanes contain a hydrogen isotope signal that originates from a hydrogen isotope signal in source water that is changed by physiological processes and interacting climatic factors during their biosynthesis. This project aims to improve our understanding of the physiological and climatic signals contained in the hydrogen isotope signal in both tree rings and leaf n-alkanes. It helps increase the useability of the hydrogen isotope signal in tree rings and helps improve the reliability of interpreting climatic signals from leaf n-alkanes. It uses a unique dataset from a field survey with samples collected multiple times during a growing season, with high temporal resolution, at one to two boreal forests in southern Finland (e.g., Leppä et al. 2022; Tang et al., 2022). This dataset is rich with information from multiple sources, such as multiple element isotope concentrations in various plant tissues and water isotope pools, as well as leaf gas exchange data, meteorological data, and eddy covariance data. The hydrogen isotope signal is traced from the climatic signal in source water, to the physiological and climatic signal in leaf water, sugars and starches and leaf n-alkanes, then from the same leaf water, sugars, and starches to bark and stem phloem sugars and starches, to high-resolution intra-annual tree ring α-cellulose. This presentation gives the project outline and some main findings.

Leppä et al. (2022) doi:10.1111/nph.18227

Tang et al. (2022) doi: 10.1093/treephys/tpac079

How to cite: Angove, C., Lehmann, M., Saurer, M., Wiesenberg, G., Young, G., and Rinne-Garmston, K.: Unlocking the physiological and climatic hydrogen isotope signal in tree rings and leaf n-alkanes in a boreal forest, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14059,, 2023.

Meisha Holloway-Phillips, Anina Wacker, Günter Hoch, Daniel B. Nelson, Marco Lehmann, and Ansgar Kahmen

Appreciation for the influence of plant metabolism on the hydrogen isotope composition (δ2H) of plant compounds has increased in recent years, adding new opportunities to understand how plants respond to environmental change. In general, where carbon supply is limited (e.g. at the beginning of the growth season, in darkness, under low CO2), the resulting δ2H of newly produced plant compounds tends to be 2H-enriched. The source of the 2H-enrichment has yet to be identified but hypotheses include: 1) a direct effect of reduced photosynthesis; 2) change in the partitioning of photoassimilates to sucrose/transitory starch; 3) use of longer-term starch reserves; and/or, 4) increased isotopic exchange with water suggesting increased metabolite cycling. To test these ideas, we utilised samples collected from a study which grew tree saplings under 100% and 6% of ambient sunlight in the field (Weber et al. 2018, New Phytologist, 222: 171-182).  In general, relative growth rate was attenuated by a species-specific amount that ensured homeostasis of non-structural carbohydrate (NSC) concentrations; however, not before an initial two-fold reduction in NSC levels – the time period the current study focussed on. Cellulose was purified and n-alkanes extracted from leaves of six deciduous species (Betula pendula, Carpinus betulus, Fagus sylvatica, Prunus avium, Quercus petraea and Tilia platyphyllos) in July 2016, around one year after the shade treatment began. The isotopic difference of cellulose between shaded and full sunlit grown leaves (εshade-sun) was significantly different from zero, with species-specific offsets ranging between 20 to 70‰. In comparison, the treatment effect was minimal for the C-chain length concentration weighted δ2H values of n-alkanes, ranging between -7 to +10‰. To narrow down the source of 2H-enrichment in leaf cellulose, the δ2H of sucrose and starch are currently being analysed in samples collected from stem wood (without bark) before bud-break in March 2016, and in leaf and stem material sampled after leaf-out in July 2016. An increase in sucrose δ2H values from shade leaves relative to controls would support Hypothesis 1 and 2; 2H-enriched storage starch relative to leaf sucrose would support Hypothesis 3; and an increase in the δ2H of sucrose in stem wood relative to storage starch (before bud-break), would support Hypothesis 4. Our study has important implications for interpreting 2H-enrichment of plant compounds with respect to reduced C supply.

How to cite: Holloway-Phillips, M., Wacker, A., Hoch, G., Nelson, D. B., Lehmann, M., and Kahmen, A.: Identifying sources of hydrogen isotope fractionation in plant carbohydrates and lipids under low carbohydrate supply, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9401,, 2023.

David Basler, Daniel B. Nelson, Jurriaan de Vos, Cristina Moreno-Gutiérrez, and Ansgar Kahmen

The analysis of the isotopic composition in herbarium specimens gives insight into the physiological responses of plants to environmental change. Specifically, the carbon isotope composition of plants is linked to the time-integrated, leaf-level intrinsic water use efficiency (i.e., the ratio of net photosynthesis over stomatal conductance), while the oxygen isotope composition is linked to leaf stomatal conductance. Thus, by combining stable isotope analyses of carbon and oxygen, trends in integrated values for net photosynthesis and stomatal conductance can be determined. Here, we present results from analyses of carbon and oxygen isotope values from over 3000 sampled herbarium specimens, that have been collected across Switzerland over the past century covering more than 80 herbaceous plant species and a wide range of habitats. While plants across most taxa and habitats have increased their intrinsic water use efficiency over the last decades, the contribution of net photosynthesis or stomatal conductance to changes in intrinsic water use efficiency differs among different plant functional groups (herbs, legumes, grasses, and sedges). Applying a multi-model approach, our study demonstrates that the carbon and water relations of plants respond to long-term changes in the environment but that the physiological nature of these responses differs among plant functional groups and the plant’s ecological niche.

How to cite: Basler, D., Nelson, D. B., de Vos, J., Moreno-Gutiérrez, C., and Kahmen, A.: Long-term physiological responses of herbaceous plants to global change from carbon and oxygen isotopes in herbarium specimen, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12998,, 2023.

An Li, Aiman Abrahim, and Simon Kelly

Stable hydrogen isotope may provide evidence to identify the botanical origin of exogenous sugars added to honey, due to a combination of factors such as the systematic global variation of meteorological waters and morphological differences affecting rates of evapotranspiration prior to water incorporation into plant carbohydrate prior to photosynthesis. Here we report an simplified method, which involves the preparation of hexamethylenetetramine (HMT), produced through chemical transformation of sugar molecules, to allow direct analysis of the carbon-bound non-exchangeable hydrogen (CBNE) by elemental analyser high temperature chromium reduction coupled to Isotope Ratio Mass Spectrometry (EA-Cr/HTC-IRMS). We have optimized the reaction conditions for oxidation and derivatisation in terms of reaction time and pH of solution. A two month-monitoring for of the repeatability of δ2H values of an HMT standard  has demonstrated stable and reliable results of this technique. The procedure is relatively straightforward, convenient and easy to apply compared with alternative reported CBNE analysis methods for foodstuffs, particularly those where isolating sugars is challenging and consensus over dual-water equilibration conditions are contentious.  Moreover, it has the advantage over other methods by avoiding the use of corrosive and explosive reagents such as sugar nitro-derivatives.  This study has also demonstrated the potential to identify from the presence of rice syrup, which is currently a significant challenge for the honey industry.

How to cite: Li, A., Abrahim, A., and Kelly, S.: Stable Isotope Analysis of Non-exchangeable Hydrogen in Sugars by Oxidation/Derivatisation to hexamethylenetetramine and Elemental Analyzer-Chromium/High Temperature Conversion- Isotope Ratio Mass Spectrometry, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16499,, 2023.

Aiman Abrahim and Simon Kelly

Polysaccharides, e.g. starch, are the most abundant biopolymers on earth. They are long chain monosaccharides linked by glycosidic bonds and are playing different important roles in plants such as energy storage (e.g. starch and glycogen) structure and growth (e.g. cellulose and pectin).The determination of carbon bound non-exchangeable (CBNE) hydrogen isotope ratios in polysaccharides are of great interest in a broad range of research areas, as they contain intrinsic information about the metabolic pathway and geographical origin of the plant, derived from water incorporated during photosynthesis. Measuring non-exchangeable hydrogen isotope ratios in starch is challenging using methods such as the dual water-equilibration technique, which are labour intensive and open to a certain degree of contention of over equilibration times, temperatures, proportions of exchangeable hydrogen and fractionation factors. We report on a new approach, to determine non-exchangeable hydrogen isotopes in starch, after hydrolysis of the biopolymer into monosaccharides followed by conversion into volatile trifluoroacetamide (TFA) derivatives and analysis by GC-CrAg/HTC-IRMS.

This new methodology (Figure.01) is rapid and simple compared to current available methods and should allow CBNE hydrogen isotope analysis to be more easily and widely used.


How to cite: Abrahim, A. and Kelly, S.: Determination of carbon bound non-exchangeable (CBNE) hydrogen isotope ratios in starch by Microwave Assisted Hydrolysis (MAH) and GC-CrAg/HTC-IRMS, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16747,, 2023.

Selina Hugger, Meisha Holloway-Phillips, Ansgar Kahmen, and Daniel B. Nelson

As plant organic compounds are formed, their hydrogen isotopic composition (δ2H) is influenced by the hydrology of the environment as well as by the plant metabolism, and hence contains information about both. Until recently, cellulose has been the only plant carbohydrate routinely measured, because it persists in tissues over long time scales and can therefore be used to understand time-integrated signals preserved in tissues like tree rings. However, knowledge gaps about how environmental and metabolic signals are imprinted in the cellulose δ2H value currently limit the interpretation of cellulose δ2H variation with respect to plant metabolism. Measuring δ2H values of biosynthetic intermediates like sugar molecules from fresh tissue offers a possibility of filling some of these knowledge gaps to better understand the cellulose δ2H signal.

Measuring δ2H values in carbohydrates is complicated by the presence of hydroxyl hydrogen. This is because this hydrogen pool can isotopically exchange with surrounding liquid water or water vapor (e.g., during sample processing and analysis), obscuring the primary plant hydrological and metabolic information contained in the isotopic values of carbon-bound hydrogen. The contribution of exchangeable hydrogen can be accounted for using dual equilibration techniques, but in most cases, these permit only analyses of bulk leaf extracted sugars. Thus, another difficulty lies in obtaining individual sugar compounds from plants. An alternative to dual equilibration is therefore to derivatize the plant sugars prior to analysis with hydrogen of known isotopic composition to form new compounds that no longer contain exchangeable hydrogen, e.g., by acetylation. Acetylation makes sugar compounds amenable to gas chromatography (GC), so this technique also allows for compound-specific analyses of multiple compounds in the same sample, such as different sugar types. GC analysis also has the advantages of requiring smaller sample amounts and providing better assurances of sample purity than are possible for bulk sample measurement approaches.

Here, we present results on streamlining our acetylation approach to facilitate rapid and cost-effective purification from sample matrices of water-soluble plant carbohydrate extracts. We acetylate whole carbohydrate extracts, and then compare recovering sugar acetates from the sample matrix by liquid-liquid separation with recovery by reverse-phase solid phase extraction (SPE) using a C18 sorbent. The liquid-liquid separation yields a higher recovery than SPE but is much more labor-intensive, whereas the SPE method can be scaled easily for higher sample throughput. Both methods proved successful for purifying water-soluble sugar samples as well as digested starch (glucose) from plant leaf, wood, and root material, yielding GC amenable sugar acetates that are soluble in acetone. Sucrose octaacetate is well resolved under normal GC measurement conditions on commonly available GC columns (e.g., DB-5), without requiring instrument modification as is the case for halogenated sample compounds.

How to cite: Hugger, S., Holloway-Phillips, M., Kahmen, A., and Nelson, D. B.: A new solid phase extraction method for purifying plant sugars for compound-specific hydrogen isotope analysis, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14146,, 2023.

Marc-Andre Cormier, Jean-Baptiste Berard, Kevin Flynn, Gael Bougaran, and Rosalind Rickaby

Since micro-organisms were first visualised by Robert Hooke and Antoni van Leeuwenhoek, bacteria and protists were quickly categorised as either primary producers or consumers and thus forming the base of the marine food web. New conceptual understanding sees this traditional dichotomy between autotrophs and heterotrophs in the marine food web replaced by one that recognises that mixotrophy is widespread. Many "phytoplankton" eat, while 50% of "microzooplankton" perform photosynthesis. This mixotrophic behaviour affects the cycling of nutrients, enhances primary production, biomass transfer to higher trophic levels, and the marine sequestration of atmospheric CO2. Moreover, the mixotrophic behaviour of many toxic protists could also be partly responsible for their ecological success and the occurrence of Harmful Agal Blooms (HABs).

While science requires a tool to measure the contributions of phototrophy and heterotrophy in plankton to help in biogeochemical modelling, my colleagues and I have already shown that hydrogen (H) isotopic signature (i.e. d2H) of lipids is uniquely sensitive to the expression of heterotrophy relative to photosynthesis in terrestrial plants and bacteria. This presentation will discuss groundwork experiments performed with Chlorella sorokiniana, Prymnesium parvum and Emiliania huxleyi that had for objective to explore whether d2H values of diverse compounds produced by protists are similarly sensitive to their central metabolic pathway. Hydrogen isotope analyses performed on organic compounds from these experiments, using an isotope ratio mass spectrometer (IRMS) coupled to a gas chromatograph (GC), suggest that H isotopic signature of lipids is indeed sensitive to the level of heterotrophic growth in diverse protists.

If this relation can be confirmed and calibrated, compound specific hydrogen isotope analyses could provide a powerful means to study the role of mixotrophy on the global carbon cycle, the cycling of nutrients and the occurrences of HABs.

How to cite: Cormier, M.-A., Berard, J.-B., Flynn, K., Bougaran, G., and Rickaby, R.: Investigating the "mixoplankton" paradigm using hydrogen isotope ratios, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16142,, 2023.

Alon Angert, Tal Weiner, Federica Tamburini, Hagit Zer, and Nir Keren

Metabolic water, the water that is produced from O2 during respiration, carries an isotopic signature that can be different from that of the water the cell is growing in. It has been well known that for large land organisms, like birds and mammals, metabolic water contributes significantly to the water balance and has an important control on the signature of the oxygen-stable-isotopes of the water inside the organism. This isotopic signature is then carried over through isotopic equilibrium to other oxygen-bearing species like phosphate. However, for small organisms like bacteria, it has been widely assumed for decades, that the large surface area to volume ratio enables a fast exchange of the cell water with the ambient water. As a result, the isotopic signature of the metabolic water will be heavily diluted and erased. In contrast, a recent work reported indirect evidence of significant control of metabolic water on the oxygen isotopes inside microbial cells. This indirect evidence is based on deviations of oxygen isotopes in phosphate from the expected equilibrium with the ambient water. Here we report the results of experiments that directly tested the possible contribution of metabolic water to phosphate oxygen isotopes in bacteria. We found that ambient water did control the oxygen isotopes in the phosphate. However, there were large deviations from the expected equilibrium. Nevertheless, we found that these deviations were not correlated with the isotopic composition of metabolic water. Hence, other mechanisms, which will be discussed, are responsible for these deviations.

How to cite: Angert, A., Weiner, T., Tamburini, F., Zer, H., and Keren, N.: Does metabolic water control the isotopic composition of water in microbial cells?, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2218,, 2023.

Travis Blake Meador, Stanislav Jabinski, Anna Mičanová, Niclas Zehetner, Karelys Umbria-Salinas, Matthias Pilecky, and Leonard Wassenaar

Dissolved organic matter (DOM) cycling is essential to understanding energy flow in aquatic ecosystems and their role as a source or sink of CO2 in the global carbon cycle. Quantifying DOM turnover and reactivity have been confounded by the barely detectable changes in the molecular composition and 13C & 15N stable-isotope compositions. We hypothesized that significant seasonal isotopic changes in environmental waters and primary biological productivity might be reflected in the H & O stable-isotope composition of DOM, providing an alternative way to assess the accumulation, turnover, and transport of DOM in aquatic environments. H & O stable-isotope analyses of DOM from lakes showed temporal coupling of water isotopes with organic molecules that accumulate in natural aquatic environments, which varied between catchments and by molecular size components of DOM. An in-situ stable-isotope labelling (HDO) experiment revealed (microbial) turnover of DOM occurred on a weekly timescale. Further development of δ2H- and δ18O-DOM analyses may improve our understanding of the provenance and processing of DOM and help better constrain unknowns in the metabolic balance of inland waters.

How to cite: Meador, T. B., Jabinski, S., Mičanová, A., Zehetner, N., Umbria-Salinas, K., Pilecky, M., and Wassenaar, L.: DOH! – The interface of isotope hydrology, ecology, and organic geochemistry, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17216,, 2023.

Posters virtual: Thu, 27 Apr, 10:45–12:30 | vHall BG

Chairpersons: Marco Lehmann, Marc-Andre Cormier, Meisha Holloway-Phillips
Youping Zhou

The 18O/16O ratio of a-cellulose in land plants has proved of interest for climate, environmental, physiological and metabolic studies. Reliable application of such ratio may be compromised by the presence of hemicellulose impurities in the a-cellulose product obtainable with current extraction methods, as the impurities are known to be isotopically different from that of the a-cellulose. We firstly compared the quality of hydrolysates of “a-cellulose products” obtained with four repre-sentative extraction methods (JAYME and WISE; BRENDEL; ZHOU; LOADER) and quantified the hemicellulose-derived non-glucose sugars in the “a-cellulose products” from 40 land grass species using GC/MS. Secondly, we performed com-pound-specific oxygen isotope analysis for the hydrolysates using GC/Pyrolysis/IRMS. These results were then compared with the bulk isotope analysis using EA/Pyrolysis/IRMS of the “a-cellulose products”. We found that the ZHOU method afforded overall the highest purity a-cellulose as judged by the minimal presence of lignin, and the second lowest presence of non-glucose sugars in the investigated grass species. Isotopic analysis then showed that the O-2~O-6 of the a-cellulose glucosyl units were all depleted in 18O by 0.0-4.3 mUr (with an average of 1.9 mUr) in a species-dependent manner relative to the a-cellulose products. The positive isotopic bias of using a-cellulose product instead of the glucosyl units stems mainly from the fact that the pentoses that dominate hemicellulose contamination in the a-cellulose product are relatively enriched in 18O (compared to hexoses) as they inherit only the relatively 18O-enriched O-2~O-5 moiety of sucrose, the common bio-chemical precursor of pentoses and hexoses in cellulose, and are further enriched in 18O by the (incomplete) hydrolysis. Failure to prepare a-cellulose with the highest possible purity, free from lignin and hemicellulose contamination, can bias predictions based on mechanistic models linking a-cellulose oxygen isotope composition to plant growth conditions.

How to cite: Zhou, Y.: On the chemical purity and oxygen isotopic composition of a-cellulose extractable from higher plants and the implications for climate, metabolic and physiological studies, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3902,, 2023.

Marina Fonti, Matthias Saurer, Trevor Porter, Mikhail Zharkov, Valentin Barinov, Anna Taynik, Alexander Kirdyanov, Anastasya Knorre, Martin Wegmann, Tatyana Trushkina, Nataly Koshurnikova, Eugene Vaganov, Vladimir Myglan, Rolf Siegwolf, and Olga Churakova (Sidorova)

Classical tree-ring parameters like tree-ring width, maximum latewood density and cell wall thickness record summer air temperature at high latitudes well and allow for the reconstruction of summer temperature over centuries and millennia. However, information about other climatic factors (e.g. moisture and sunshine duration) is limited in these proxies, especially for temperature-limited environments in subarctic forests growing on permafrost soils. The application of stable hydrogen and oxygen isotopes can provide complementary information about moisture changes and solar irradiation.

Solar irradiation and its seasonal distribution play an important role for trees in terms of photosynthesis and carbohydrate production, which can influence deuterium variations in organic matter in addition to hydrological processes. We found that hydrogen and oxygen isotopes in larch tree-ring cellulose from Siberia show a strong link with summer sunshine duration during the growth season. Negative correlations with sunshine duration during autumn of the previous year and winter of the current year can be related to the lack of light during polar nights at subarctic sites (> 60º N) and lack of needles in larch trees to produce photosynthates in a cold environment. Indirect effects might also arise as a high amount of winter sunshine means persistent high-pressure systems with low precipitation, therefore negatively affecting snow accumulation, which is an important water source after snow melt.

Uptake of winter precipitation is possible in the warming spring and summer months after snowmelt and thawing of the active soil layer, resulting in significant correlations between tree-ring oxygen values and winter-spring air temperatures. Oxygen isotopes in organic matter are influenced by variations in the isotopic composition of source water, which is closely related to that of precipitation and soil water (though modified by evaporation at the soil surface).

Furthermore, we observed that summer vapor pressure deficit is positively and significantly recorded in stable oxygen isotopes from northeastern Siberia, while continuously represented through spring-summer months in western Canada. Hydrogen tree-ring isotopes from the Canadian subarctic recorded a negative significant correlation with summer relative humidity, opposite to northeastern Siberia.

The application of dual hydrogen and oxygen stable isotopes in tree rings can expand our knowledge beyond traditional summer air temperature reconstructions and will help to improve climate reconstructions over the past millennia.

Acknowledgements: This work was supported by the project RSF 21-17-00006.

How to cite: Fonti, M., Saurer, M., Porter, T., Zharkov, M., Barinov, V., Taynik, A., Kirdyanov, A., Knorre, A., Wegmann, M., Trushkina, T., Koshurnikova, N., Vaganov, E., Myglan, V., Siegwolf, R., and Churakova (Sidorova), O.: Beyond traditional summer air temperature signals in subarctic tree rings using hydrogen and oxygen isotopes, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11722,, 2023.