BG2.1 | Application of Stable Isotopes in Biogeosciences and Climate Studies
Application of Stable Isotopes in Biogeosciences and Climate Studies
Convener: Michael E. Böttcher | Co-conveners: Amelia DaviesECSECS, Naizhong Zhang, Claudia VoigtECSECS, Kirstin Dähnke, Anne-Désirée SchmittECSECS, Gerd Gleixner
| Thu, 18 Apr, 14:00–15:45 (CEST)
Room 2.95
Posters on site
| Attendance Thu, 18 Apr, 10:45–12:30 (CEST) | Display Thu, 18 Apr, 08:30–12:30
Hall X1
Orals |
Thu, 14:00
Thu, 10:45
This session is open to all contributions in biogeochemistry, ecology, and climate studies, where stable isotope techniques are used as analytical tools, with foci both on stable isotopes of light elements (C, H, O, N, S, …) and new systems (triple oxygen, clumped and metal isotopes). We welcome studies from both terrestrial and aquatic (including marine) environments as well as methodological, experimental and theoretical studies that introduce new approaches or techniques (including natural abundance work, labelling studies, multi-isotope approaches).

Orals: Thu, 18 Apr | Room 2.95

Isotope hydrology
On-site presentation
Stefan Terzer-Wassmuth, Luis Araguas-Araguas, Leonard I. Wassenaar, Lucilena R. Monteiro, and Christine Stumpp

During the past decade, the rare O isotope 17O and the 17O-excess became attractive for potential new applications in hydrology, climatology, and broader oxygen isotope research. Although laser-based analysers are technologically capable of the needed Δ′17O assays, progress was hindered by the metrological challenges and the absence of fundamental spatiotemporal data on precipitation inputs. Uncertainties surrounding the input function of the water cycle complicate advancements of 17O as a tracer. This “emerging tracer dilemma” is a potential obstacle for further triple-O isotope research.

In this work, >3500 archived water samples from the Global Network of Precipitation (GNIP) sample archives (2015-2021) were re-analysed for  for δ17O and Δ′17O. For >60 GNIP stations, four or more years’ of samples were analysed, assessing the seasonality of Δ′17O, and constructing δ17O/ δ18O Local Meteoric Water Lines (LMWL). This global dataset allowed for a first-ever comprehensive assessment of the spatial patterns of δ17O/ δ18O LMWLs, and to devise a first-ever precipitation-weighted Global Meteoric Water Line (GMWL): δ′17O = 0.5280 ± 0.0002 δ′18O + 0.0153 ± 0.0013. This GMWL definition is similar to previous efforts albeit with a lower ordinate intercept.

We further analysed the Δ′17O of a 6-year daily/fortnightly precipitation sampling in Vienna as an example of seasonal isotopic variations at synoptic weather patterns’ resolution. Air moisture sources were determined by backwards trajectory analysis and corroborated with synoptic weather data from Austria’s meteorological service. The Δ′17O values correlated with δ18O seasonality. A comparison with the deuterium excess patterns (stemming from the Atlantic and Mediterranean domains) demonstrated that the “two excesses” carried different signals. While elevated d-excesses
mainly came from the central/eastern Mediterranean Sea or easterly continental sources during all seasons, we found elevated Δ′17O precipitation originated only from northerly or north-easterly sources, and predominantly during the winter season.

Finally, we present pilot Vienna precipitation events sampled at sub-hourly (to 5-minute) resolution, which included both cyclonic and convective rainfall events, which demonstrate the interplay of moisture sources using triple oxygen isotopes and deuterium excess. This work will help to shape our understanding of δ17O and Δ′17O in Earth’s precipitation, despite the ongoing metrological challenges faced, and promote discussion regarding the scientific value of routine measurements for triple-oxygen isotopes in precipitation.

How to cite: Terzer-Wassmuth, S., Araguas-Araguas, L., Wassenaar, L. I., Monteiro, L. R., and Stumpp, C.: Measuring δ17O and Δ′17O in precipitation across various spatial and temporal scales: spanning from global to local and from multi-year to sub-hourly resolutions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3596,, 2024.

Carbon cycle
On-site presentation
Marie Pesnin, Justin Chaillot, Thibault Clauzel, Claire Rollion-Bard, Sebastien Nomade, Samir Kassi, Franck Lartaud, and Mathieu Daëron

Kinetic isotopes effect (KIEs) describes a very common phenomenon related to change in chemical reaction rate due isotopic substitution. If in biological sciences, KIEs has received a lot of interest with the aim at understanding reaction mechanisms, their control on the isotopic composition of biogenic carbonate has long been overlooked. However, the initial assumption that isotopic fractionation primarily reflects a thermodynamic equilibrium process in the H2O-DIC-CaCO3 system is challenged by a growing number of observations. Not accounting for these disequilibrium effects leads to inaccurate estimates of carbonate growing temperature. In this scientific context, Triple oxygen isotopes systematic can help constraining kinetics isotopes fractionation associated with metabolic reactions implicated in biocarbonates formation. We thus took advantage from recent development in spectroscopic technique (VCOF-CRDS) to measured O17isotopic anomalies in CO2produced by carbonate acid reaction [1]. These samples were also analyzed for their δ13C, δ18O and Δ47 composition using a more classical mass spectroscopy technic. In this contribution we investigated cold-water corals (CWC) known to display strong isotopic disequilibria. For this 1st application, we selected four modern CWC species for which calcification conditions (T, S, pH, δ18Owater, Δ17Owater and δ13CDIC) are independently constrained. The measured isotopic signatures were compared to their respective expected values based on environmental constrains, assuming “pseudo-equilibrium” carbonate precipitation. In particular, corals Δ17O signatures were compared to the newly established equilibrium for O17 fractionation between calcite-water based on slow growing carbonates from Laghetto Basso and Devils Hole, measured using the same VCOF-CRDS technic [2]. We finally compared our experimental data with theoretical predictions for KIEs on DIC isotopic composition [3]. Interestingly, the correlation slope among Δ47 - Δ17O disequilibrium differ from the previous one derived from dual clumped (Δ47 - Δ48) isotopic measurements of the same species [4]. This founding suggesting that other biological parameter(s) should be taken into account to resolve CWC isotopic disequilibria.

[1] Chaillot. J., Daëron. M., Casado, M., Landais. A., Pesnin. M., Clauzel. T., Kassi. S. (in prep) Triple oxygen analyses of carbon dioxide, water and carbonates using VCOF-CRDS.

[2] Clauzel, T., Chaillot, J., Pesnin, M., Jautzy, J., Kessy, S., Daëron, M. (in prep) Advancing triple oxygen isotope analysis of carbonate and water using V-shaped Cavity Optical Feedback Cavity Ring-Down Spectroscopy (VCOF-CRDS): Calibration and implications for paleoclimate reconstruction.

[3] Guo. W. (2020). Kinetic clumped isotope fractionation in the DIC-H2O-CO2 system: Patterns, controls, and implications. Geochimica et Cosmochimica Acta, 268, 230-257.

[4] Davies. A. J., Guo. W., Bernecker. M., Tagliavento. M., Raddatz. J., Gischler. E., Floter. S., Fiebig. J. (2022). Dual clumped isotope thermometry of coral carbonate. Geochimica et Cosmochimica Acta, 338, 66-78.

How to cite: Pesnin, M., Chaillot, J., Clauzel, T., Rollion-Bard, C., Nomade, S., Kassi, S., Lartaud, F., and Daëron, M.: Contribution of triple oxygen isotopes measurement by Cavity Ring Down spectroscopy and Clumped isotopes to the understanding of kinetics effect in cold water corals., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5836,, 2024.

On-site presentation
Stefano Bernasconi, Nathan Looser, Nico Kueter, Ricarda Rosskopf, and Jordon Hemingway

Since its establishment almost 20 years ago, carbonate clumped isotope thermometry (Δ47, Δ48) has grown to the most widely applied branch of the rapidly evolving field of clumped isotope geochemistry. An increasing number of laboratories worldwide is implementing this technique and applying it to solve a broad range of Earth science questions. The introduction of carbonate-based standardisation (Bernasconi et al. 2021), together with recent efforts to improve temperature calibrations (e.g. Anderson et al. 2021), has solved inter-laboratory differences and greatly improved the confidence in temperature reconstructions based on Δ47. Discrepancies in absolute temperatures using different calibrations are now on the order of 1-2°C only. The next frontier in carbonate clumped isotopes is Δ48 which is even more analytically challenging than Δ47 but has the potential to solve long standing questions of equilibrium/disequilibrium precipitation of carbonates and better understand processes of biomineralization. An important remaining field that requires further research is related to the preservation of the original clumped isotope temperatures in deep time samples and the kinetics of C-O bond reordering. In this contribution, we will review the state-of-the-art analytical methods and calibrations and discuss open challenges in interpreting clumped isotope signatures of biogenic and inorganic carbonates with bond reordering models.

Bernasconi et al. (2021) InterCarb: A Community Effort to Improve Interlaboratory Standardization of the Carbonate Clumped Isotope Thermometer Using Carbonate Standards. Geochemistry, Geophysics, Geosystems, 22(5),e2020GC009588..

Anderson et al. (2021) A unified clumped isotope thermometer calibration (0.5–1100°C) using carbonate‐based standardization. Geophysical Research Letters, 48, e2020GL092069.

How to cite: Bernasconi, S., Looser, N., Kueter, N., Rosskopf, R., and Hemingway, J.: Clumped isotopes in carbonates: state of the art and open questions , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7981,, 2024.

On-site presentation
Ralf Conrad and Peter Claus

Formate is energetically equivalent to hydrogen and thus, is an important intermediate during the breakdown of organic matter in anoxic rice field soils and lake sediments. Formate is a common substrate for methanogenesis, homoacetogenesis and sulfate reduction. However, how much these processes contribute to formate degradation and fractionate carbon stable isotopes is largely unknown. Therefore, we measured the conversion of formate to acetate, CH4 and CO2 and the δ13C of these compounds in samples of paddy soils from Vercelli (Italy) and the International Rice Research Institute (IRRI, the Philippines) and of sediments from the NE and SW basins of Lake Fuchskuhle (Germany). The samples were suspended in phosphate buffer (pH 7.0) both in the absence and presence of sulfate (gypsum) and of methyl fluoride (CH3F), an inhibitor of aceticlastic methanogenesis. In the paddy soils, formate was found to be an excellent substrate for acetate formation, while CH4 was mainly produced from acetate. Acetate was also produced in the presence of sulfate. The produced acetate was strongly depleted in 13C relative to formate (about -50‰ to-25‰), but the consumption of formate itself displayed only a small isotope enrichment factor on the order of -8‰ to -6‰. Therefore, it is likely that formate was disproportionated to 13C-depleted acetate and 13C-enriched CO2. The δ13C of CO2 was indeed slightly higher than that of formate. Acetate was most likely produced by homoacetogenesis via the Wood-Ljungdahl pathway. Methane was only a minor product and was mainly produced from the acetate as its production was inhibited by CH3F. The homoactogenic bacteria in the paddy soils apparently competed well with both methanogenic and sulfate-reducing microorganisms, when formate was the substrate. In the lake sediments, the product spectrum was similar, but only under methanogenic conditions. In the presence of sulfate, however, acetate and CH4 were only minor products and no enrichment factor was detectable when formate was degraded to mainly CO2. Hence, homoacetogenesis was the major anaerobic degradation pathway of formate. Formate-dependent methanogenesis was negligible, and sulfate-dependent oxidation was only operative in the lake sediments but not in the paddy soils.

How to cite: Conrad, R. and Claus, P.: Formate consumption and stable carbon isotope fractionation in anoxic rice field soils and lake sediments, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2895,, 2024.

Sulfur cycle
On-site presentation
Alexey Kamyshny, Khoren Avetisyan, Natella Mirzoyan, and Rayford Payne

Lake Sevan is a meso-eutrophic water body, which was severely impacted by anthropogenic level decrease, pollution and eutrophication during the last century. Starting in the 1970s, a decrease in the water level and an increase in dissolved inorganic nitrogen concentrations resulted in oxygen depletion in the hypolimnion of the lake during summer–autumn thermal stratification of the water column. Our work shows that in October 2019, the redox conditions in the hypolimnion progressed not only to full depletion of oxygen and nitrate, but to the formation of a hydrogen sulfide-rich deep-water layer, which covers 66% of lake’s bottom and accounts for 19% of its water volume. Concentrations of hydrogen sulfide in the hypolimnion of Major and Minor Sevan in October were as high as 9 and 39 μM, respectively.

Triple sulfur isotope composition of sulfate and hydrogen sulfide in the water column of the lake provides further constraints on the biogeochemical processes which result in the formation of hydrogen-sulfide hypolimnion. Values of δ34S for hypolimnetic sulfide are lower by only 7–12 ‰ compared to epilimnetic sulfate, while δ33S values of sulfide are similar to the δ33S values of sulfate. These isotopic fingerprints are not consistent either with microbial sulfate reduction in the water column or with its combination with re-oxidative sulfur cycle as the sources of hydrogen sulfide in the hypolimnion. We attribute the formation of a sulfidic deep-water layer to a combination of microbial sulfate reduction in the water column and diffusion of hydrogen sulfide from the sediments.

How to cite: Kamyshny, A., Avetisyan, K., Mirzoyan, N., and Payne, R.: Triple sulfur isotope constraints on the sulfur cycling in Lake Sevan, Armenia, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4590,, 2024.

Nitrogen cycle
On-site presentation
Maren Voss, Anne Breznikar, Iris Liskow, Daniel Poenisch, and Gregor Rehder

Along the German coastline of the Baltic Sea are numerous former coastal fens. The originally approx. 40,000 hectares of peatland that were regularly flooded are now mostly diked, drained and are mainly used for agriculture. In order to be prepared for rising sea levels in the future, attempts are being made to determine the consequences of renewed flooding for the development of the fen and the adjacent Baltic Sea. A first test area was a former peatland in Drammendorf on the island of Ruegen, Germany. It had been rewetted in a major campaign lead by the Baltic Sea Foundation. The other area, Karrendorf, had been flooded already 30 years ago. The two coastal fens had different periods of waterlogging and were studied comparatively over the course of a year. In addition to the typical seasonality, which is reflected in the same temperature and oxygen content at both sites and the adjacent bays, there are striking differences in nutrient concentrations and isotope signatures of organic matter and nitrate, some of which can be traced back to the history of the areas as agricultural land. Shortly after its rewetting in winter, for example, nitrate concentrations in Drammendorf were several times higher than in Karrendorf and nitrous oxide saturations were up to 4000 %.

We found that the longer the area was flooded and nutrients released to the overlying waters, the less nutrients are discharged into the adjacent Baltic Sea. This finding was not only reflected by lower nutrient concentrations in the surface water of Karrendorf, but also in much lower porewater nutrient concentrations. Moreover, we saw a close coupling of the microbial processes in the overlying water with the soils. Nitrification, which converts ammonium from decomposition processes into nitrate, was clearly recognizable in the nitrogen and oxygen isotopes of nitrate despite low rates. However, high δ18O values of nitrate indicate precipitation as another possible source of nutrients. In addition, the isotope values of the organic matter show that there is an intensive exchange between the Baltic Sea and the coastal fens, whereby Drammendorf is more strongly characterized by marine organic matter inflow than Karrendorf. Thus, the flooding of coastal peatlands initiates lateral transport across the terrestrial-marine interface, while the microbial processes play more of a role in the interaction between soil and water.

For future management, the soil composition and history should always be considered and the intensity of exchange with coastal waters taken into account so that these areas do not become hot spots of eutrophication due to their large nutrient reservoirs.

How to cite: Voss, M., Breznikar, A., Liskow, I., Poenisch, D., and Rehder, G.: Response of two coastal peatlands to the duration of rewetting and the release of nutrients, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5453,, 2024.

On-site presentation
Anja S. Studer, Jochem Baan, and Moritz F. Lehmann

The nitrogen (N) isotopic composition of diatom frustule-bound organic matter (δ15NDB) from sedimentary archives has been used as a promising proxy indicator to reconstruct nitrate utilization in the high-latitude oceans on different timescales. The advantage of this proxy over conventional N isotopic approaches, such as measuring δ15N values of the bulk sediment, is that δ15NDB is thought to be protected from diagenetic alteration and bacterial degradation. Despite the fact that the δ15NDB proxy has been applied in palaeoceanographic research for two decades, little is known about the propagation of the δ15N signature of assimilated nitrate into biomass δ15N and subsequently into δ15NDB, and to what extent N-isotope fractionation during frustule-bound N synthesis varies among species and with environmental conditions. Only few δ15NDB data exist for living diatoms in natural environments or laboratory cultures, and implications for paleo-environmental reconstructions appear controversial between existing studies. Here, we present novel constraints on the relationship between δ15N values of nitrate, diatom bulk biomass, and diatom frustule-bound N across samples from different natural environments and from controlled mono-specific diatom cultures. While previous ground-truthing work has focussed on marine diatom species both in culture and in the ocean, we extend our study to freshwater species and lacustrine environments. We find that, in mono-specific diatom cultures, δ15NDB values are generally relatively close to biomass δ15N values, irrespective of the variable 15N-fractionation imparted by nitrate assimilation. Similarly, analysis of diatom samples from natural environments revealed little offset between δ15NDB and bulk biomass δ15N values in samples that are near mono-specific. By contrast, in more mixed-species samples, δ15NDB values can be shifted in both directions relative to biomass δ15N values, possibly as a result of i) species-specific N isotope fractionation during frustule-bound N synthesis, and/or ii) non-uniform contribution of N to the total biomass and diatom-bound N pools between different species.

How to cite: Studer, A. S., Baan, J., and Lehmann, M. F.: Transfer of the nitrogen isotope signature from the nitrate pool to the diatom biomass and into the diatom frustule, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10367,, 2024.

On-site presentation
Ilann Bourgeois, Jean-Christophe Clement, Lionel Bernard, Nicolas Caillon, Cedric Dentant, Leon Lepesant, Thomas Pommier, and Joel Savarino

Glacial forelands are expanding worldwide due to glacier shrinkage1, exposing new areas prone to the development of post-glacial ecosystems2,3. Nitrogen (N) is generally considered as a (co-)limiting nutrient in alpine regions, and deposition of atmospheric N, mainly emitted due to fossil fuel combustion, has for long been admitted as the main source of N4. However, other N sources such as glacial meltwaters5, long-range transport of fertilizers6 or bedrock erosion7 have recently been suspected of playing a more significant role than previously thought and could drive the establishment of pioneer microbial and plant communities in glacial forelands.

Here, we show the isotopic composition and concentration of nitrate (δ15N, δ18O, Δ17O) and ammonium (δ15N) in glacial meltwaters, soils and plants from three glacial forelands in the French Alps. Samples were collected along transects expanding from the glacier front to areas deglaciated around 60 years ago. We find that the contribution of atmospheric deposition to the nitrate pool in soils decreases as time since deglaciation increases, but never exceeds 40%, not even at the glacier front where soils are entirely mineral with no detectable nitrification enzymatic activity. This pattern suggests that bedrock nitrogen and glacial meltwaters are the main N sources in post-glacial ecosystems and calls for a better quantification of those inputs.  


(1)             Hugonnet, R.; McNabb, R.; Berthier, E.; Menounos, B.; Nuth, C.; Girod, L.; Farinotti, D.; Huss, M.; Dussaillant, I.; Brun, F.; Kääb, A. Accelerated Global Glacier Mass Loss in the Early Twenty-First Century. Nature 2021, 592 (7856), 726–731.

(2)             Bosson, J. B.; Huss, M.; Cauvy-Fraunié, S.; Clément, J. C.; Costes, G.; Fischer, M.; Poulenard, J.; Arthaud, F. Future Emergence of New Ecosystems Caused by Glacial Retreat. Nature 2023, 620 (7974), 562–569.

(3)             Ficetola, G. F.; Marta, S.; Guerrieri, A.; Gobbi, M.; Ambrosini, R.; Fontaneto, D.; Zerboni, A.; Poulenard, J.; Caccianiga, M.; Thuiller, W. Dynamics of Ecological Communities Following Current Retreat of Glaciers. Annu. Rev. Ecol. Evol. Syst. 2021, 52(1), 405–426.

(4)             Holtgrieve, G. W.; Schindler, D. E.; Hobbs, W. O.; Leavitt, P. R.; Ward, E. J.; Bunting, L.; Chen, G.; Finney, B. P.; Gregory-Eaves, I.; Holmgren, S.; Lisac, M. J.; Lisi, P. J.; Nydick, K.; Rogers, L. A.; Saros, J. E.; Selbie, D. T.; Shapley, M. D.; Walsh, P. B.; Wolfe, A. P. A Coherent Signature of Anthropogenic Nitrogen Deposition to Remote Watersheds of the Northern Hemisphere. Science 2011, 334 (6062), 1545–1548.

(5)             Saros, J. E.; Rose, K. C.; Clow, D. W.; Stephens, V. C.; Nurse, A. B.; Arnett, H. A.; Stone, J. R.; Williamson, C. E.; Wolfe, A. P. Melting Alpine Glaciers Enrich High-Elevation Lakes with Reactive Nitrogen. Environ. Sci. Technol. 2010, 44 (13), 4891–4896.

(6)             Hundey, E. J.; Russell, S. D.; Longstaffe, F. J.; Moser, K. A. Agriculture Causes Nitrate Fertilization of Remote Alpine Lakes. Nat. Commun. 2016, 7 (1), 10571.

(7)             Houlton, B. Z.; Morford, S. L.; Dahlgren, R. A. Convergent Evidence for Widespread Rock Nitrogen Sources in Earth’s Surface Environment. Science 2018, 360 (6384), 58–62.

How to cite: Bourgeois, I., Clement, J.-C., Bernard, L., Caillon, N., Dentant, C., Lepesant, L., Pommier, T., and Savarino, J.: Unlocking the nitrogen cycle in glacial forelands: an isotopic perspective, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12077,, 2024.

Isotopes and health
On-site presentation
Isotopic composition in blood as a diagnostic tool of health in large Arctic wildlife
Sophia Hansson, Floris van Beest, Niels Martin Schmidt, Gaël Le Roux, Alexandra Gourlan, and Atcaf Team

Posters on site: Thu, 18 Apr, 10:45–12:30 | Hall X1

Display time: Thu, 18 Apr 08:30–Thu, 18 Apr 12:30
Anna-Kathrina Jenner, Rhodelyn Saban, Catia Milene Ehlert von Ahn, Julia Westphal, Patricia Roeser, Iris Schmiedinger, Jürgen Sültenfuss, and Michael Ernst Böttcher

The impact of freshwater sources like surface river and submarine groundwater discharge (SGD) on the coastal water, the element balance therein, and the associated biogeochemical transformations within the subterranean estuary is currently a matter of intense debate and investigation. A quantification of freshwater mixing in coastal areas has been found to be challenging. In this sense the combination of stable water isotopes with further (isotope) hydro(bio)geochemical tracers provides a fundamental valuable tool to identify different freshwater sources found in the mixing zone with seawater.

Here, we report the geochemical and isotopic composition of porewaters of permeable sediments in front of a coastal peatland, the Huetelmoor (southern Baltic Sea). Gradients in pore water measurements from 5 m long stationary porewater lances are used to calculate the zero-salinity (ZS) component. The application of binary mixing approaches on water isotopes and conservative elements on the compositional gradients yields temporarily relatively stable ZS compositions but with substantial isotope differences for spatially distant lances. This indicates a subterranean estuary under steady-state conditions with different fresh waters entering the coastal area. At least two freshwater sources can be identified for sediments impacted by SGD without substantial impact of short-term hydrological or meteorologic processes. These results are compared to the composition of potential endmembers, such as the local surface and groundwaters, the local meteoric water line, and the open brackish Baltic Sea.

Besides stable isotopes, also dissolved major and minor elements were used to characterize the biogeochemical processes leading to the non-conservative behavior of nutrients, the carbon system, and trace elements. In addition, tritium-noble gas dating of the pore waters allows for an estimate of the fresh water residence time before mixing with the brackish Baltic Sea water.

Results will be discussed in the context of other SGD sites along the northern German coast.


Acknowledgement for support by DFG RTG Baltic TRANSCOAST, DFG-KiSNet, BMBF COOLSTYLE/CARBOSTORE, DAAD, and Leibniz IOW

How to cite: Jenner, A.-K., Saban, R., Ehlert von Ahn, C. M., Westphal, J., Roeser, P., Schmiedinger, I., Sültenfuss, J., and Böttcher, M. E.: Fresh water sources for submarine groundwater discharge to the southern Baltic Sea , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18347,, 2024.

Rhodelyn Saban, Anna-Kathrina Jenner, Catia Milene Ehlert von Ahn, Iris Schmiedinger, and Michael Böttcher

The interface between the terrestrial and marine environments regulates the interactions between the adjoining domains. Natural and anthropogenic alterations influence the processes and exchanges of materials. This study aims to determine the biogeochemical processes before and after anthropogenic changes in the coastal protection at the southern Baltic Sea coast proximal to a peatland (Hütelmoor, Rostock, Germany). Spatial and temporal investigations, with the use of stationary porewater lances, characterize the dynamics of biogeochemical transformation processes. Porewaters were measured for in-situ physico-chemical parameters and analyzed for dissolved organic and inorganic carbon (DOC and DIC), major ions, redox-sensitive elements and nutrients concentrations. Stable isotopes (ẟ13C-DIC and -DOC, ẟ2H- and ẟ18O-H2O, and ẟ34S- and ẟ18O-SO4, and ẟ34S-H2S) and non-stable isotopes (223Ra, 224Ra) were also measured. Results indicate high concentrations of DOC which may have originated from peat degradation and high concentrations of DIC, which may have been derived from organic matter mineralization, terrestrial and marine carbonate dissolution, and Baltic Sea-derived DIC. Minor contributions from CH4 oxidation cannot be ruled out. Diagenetic transformations are also reflected in the vertical profiles of redox-sensitive ions (such as Fe, Mn, SO4 and H2S). Sulfate, dominantly from Baltic Sea water and microbial reduction-oxidation, influences diagenesis. Water is a mixture of different brackish and freshwater sources.  Moreover, submarine groundwater discharge (SGD) was observed from 150 cmbsf and also evident in 224Ra activities. With the changes in the coastal protection status, internal transport processes of porewaters in the sediment are evidently influenced by the hydrogeodynamics along the coastline on a local to regional scale.

How to cite: Saban, R., Jenner, A.-K., Ehlert von Ahn, C. M., Schmiedinger, I., and Böttcher, M.: Temporal and spatial investigations of the isotope biogeochemistry of a coastal peatland area under sporadic flooding , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3580,, 2024.

Miguel Bernecker, Magali Bonifacie, Philip Staudigel, Daniel Petrash, Eiken Haussühl, Martin Dietzel, Amelia Davies, Mattia Tagliavento, Julien Siebert, Nicolas Wehr, and Jens Fiebig

Dual-clumped isotope thermometry relies on the joint measurement of ∆47 and ∆48 in CO2 evolved from phosphoric acid digestion of carbonates (Fiebig et al., 2019). The benefit over ∆47-only measurements is its capability to identify if ∆47was affected by rate-limiting kinetics in addition to temperature, and to reconstruct accurate carbonate formation temperatures devoid of this kinetic bias (Bajnai et al., 2020).

Direct measurements of ∆63 and ∆64 in carbonates are technically not feasible. During acid digestion of carbonates, fractionations of clumped isotopes (∆63 → ∆47 and ∆64 → ∆48) occur, but the exact magnitudes of acid fractionation factors (AFFs) are not consistently established and vary across different published sources.

Theoretical models by Guo et al. (2009) indicate cation-dependent differences in AFFs for different carbonate mineralogies. Follow-up empirical studies yielded somewhat inconsistent results for ∆47 – some did not observe any differences in AFFs (e.g., Defliese et al., 2015 for calcite, aragonite, and dolomite; Bonifacie et al., 2017 for calcite and dolomite), whereas others did report differences (e.g., Murray et al., 2016 for calcite and dolomite; Müller et al., 2017 for calcite, aragonite, dolomite, and magnesite).

Advancements in gas source mass spectrometry have led to significant improvements in the long-term external repeatability of clumped isotope measurements, e.g., from > 20 ppm to 7-9 ppm for ∆47 (Bernecker et al., 2023). With this improved analytical set-up, we analyzed an assorted collection of scrambled aragonite, calcite, dolomite, siderite and witherite samples for their ∆47 and ∆48 values. We show that cation substitution and mineralogy have no effect on AFFsfor aragonite , calcite, dolomite and witherite. Moreover, the dual clumped isotope compositions of additionally investigated low-temperature aragonite and dolomite samples plot indistinguishable from the calcite equilibrium line. Altogether these findings strongly imply that the ∆47-∆48 -T framework established for calcite (Fiebig et al., 2021) is extendable to aragonite and dolomite.



Defliese, W.F. et al. Chem. Geol. 396, 51–60 (2015).

Murray, S.T. et al. Geochim. Cosmochim. Acta 174, 42–53 (2016).

Müller, I.A. et al. Chem. Geol. 449, 1–14 (2017).

Bonifacie M. et al. Geochim. Cosmochim. Acta 200, 255-279 (2017).

Fiebig, J. et al. Chem. Geol. 522, 186–191 (2019).

Bajnai, D. et al. Nat. Commun. 11, 4005 (2020).

Fiebig, J. et al. Geochim. Cosmochim. Acta 312, 235–256 (2021).

Bernecker, M. et al. Chem. Geol. 642, 121803 (2023).

How to cite: Bernecker, M., Bonifacie, M., Staudigel, P., Petrash, D., Haussühl, E., Dietzel, M., Davies, A., Tagliavento, M., Siebert, J., Wehr, N., and Fiebig, J.: Investigating the effect of cation substitution and mineralogy on the dual clumped isotope composition of carbonates, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11056,, 2024.

Andrea Czébely, Marianna Túri, Diána Kiss, Gábor Újvári, Titanilla Kertész, and László Rinyu

Quantitative reconstruction of temperature remains the major focus and challenge of paleoclimate research, especially in the terrestrial realm. This study is aimed at testing the usefulness of Δ47 of earthworm’s biospheroids (EBS) as a temperature proxy by comparing the EBS-derived T47 values to those obtained from previously studied land snails. For this purpose, the Dunaszekcső loess record in southern Hungary has been selected, which is an extensively studied section with a high resolution 14C chronology [1,2,3], revealing stadial-interstadial variations in sedimentation rates.

Sixteen samples were collected in 10 cm resolution from the loess layers between 850-770 cm and 695-615 cm representing the GI-5.1 (30.6-30.8 ka) and GI-3.1 (27.5-27.8 ka) periods and surrounding stadials [4]. The associated temperature was calculated previously between 8-15 °C [4] based on the clumped isotope compositions of mollusc shells of these layers.

The impact of sample preparation methods on Δ47 values of secondary carbonates is unknown and is a potential concern. To test this, two different sample preparation methods were applied on Trochulus hispidus shells recovered from the mentioned loess layers: 1) treatment in 1 m/m% HCl solution and 2) treatment with 3 m/m% H2O2 solution under vacuum and in ultrasonic bath in ultrapure water. The reconstructed temperatures based on the Δ47 values of the snail shells typically fell between 7-15 °C (HCl pretreatment) and 9-14 °C (H2O2 pretreatment), in very good agreement with previous published land snail T47 data [4]. The average temperatures obtained from biospheroids reveal the same stadial-interstadial temperature pattern previously reconstructed by molluscs. The mean T47 values of the two pretreatment methods are within the expected temperature range derived from the snail shells.

Clumped isotope analysis was also performed on biospheroid samples from the same layers, and the calculated temperatures were compared with those obtained from snail shells by Újvári et al. [4]. To demonstrate that the biospheroid carbonates from the same layers are of the same age as the examined molluscs, we performed radiocarbon dating on the biospheroids. Our primary goal is to investigate whether the Δ47 compositions are affected by the so-called vital effect and to what extent the formation of biospheroid carbonates is influenced by these kinetic effects. To achieve this goal, a long-term experiment is going on. We perform climate chamber experiments [5,6,7] at temperatures of 8, 11 and 15 °C. Other variables, including relative humidity, CO2 concentrations and the stable isotope compositions of diet and spray liquid are also controlled. The first results will be presented.



[1] Újvári, G. et al. 2014, Quaternary Science Review Vol. 106, 140-154

[2] Újvári, G. et al. 2016, Quaternary Geochronology Vol. 35, 43-53

[3] Újvári, G. et al. 2019, Palaeogeography, Palaeoclimatology, Palaeoecology Vol. 518, 72–81

[4] Újvári, G. et al. 2021, AGU, Advancing Earth and Space Science, Paleoceanography and Paleoclimatology, Volume 36, Issue 8

[5] Canti, M.G. 2009, Soil Biology & Biochemistry Vol. 41, 2588-2592

[6] Lambkin, D.C. et al. 2011, Applied Geochemistry Vol. 26, S64-S66

[7] Versteegh, E.A.A et al. 2014, Soil Biology and Biochemistry Vol. 70, 159-161

How to cite: Czébely, A., Túri, M., Kiss, D., Újvári, G., Kertész, T., and Rinyu, L.: Clumped isotope temperatures from secondary carbonates in loess: comparability of different preparation methods of snail shells and earthworm biospheroids, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16279,, 2024.

Gabriela Sanchez Ortiz, Marlene Löberbauer, Payal Banerjee, Nevena Tomašević, Oleg Mandic, Davor Pavelić, Vedad Demir, Zachary Sharp, Maud Meijers, and Jeremy Rugenstein

The Dinaric Alps formed as a result of the collision between the Adria microplate with Eurasia during ongoing closure of the Tethys Ocean. However, there remain a number of questions regarding the mechanisms that created and sustained the high topography (maximum modern elevation of ~2500 m) of this region. We take advantage of a series of lacustrine basins—known as the Dinaride Lake System (DLS)—that formed in the Early and Middle Miocene to constrain paleo-elevations of the Dinaric Alps using stable isotope paleoaltimetry. We collected authigenic lacustrine carbonate samples from six basins in Croatia and Bosnia and Herzegovina that span the range from sea-level to high-elevation (~1200 m) and measured these samples for δ18O. In addition, we also collected stream samples that span the range to constrain the modern change in δ18O across the Dinaric Alps. Stable-isotope paleoaltimetry is based on the concept that, as moist air parcels are forced upwards by orography, 18O is preferentially removed by the resulting precipitation, resulting in lower δ18O at higher-elevations and in the lee of ranges. Today, meteoric water δ18O is high (~ -6‰) at the coast and is ~5‰ lower at the crest of the range (~ -11‰). However, Middle Miocene lacustrine carbonate δ18O is high (~ -3‰) at the crest of the range and lower (~ -6‰) at the coast. Because lacustrine carbonate δ18O is frequently impacted by evaporation, we analyzed a subset of our samples for Δ17O, which is sensitive to the degree of evaporation. These carbonates have Δ17O values ranging from -68 to -150 per meg. Using our Δ17O data and a model of lake evaporation, we reconstruct the unevaporated meteoric water δ18O. Our preliminary results show a similar trend as in the modern, with higher δ18O values at the coast and lower δ18O at the crest of the range. Reconstructed unevaporated meteoric water δ18O at the crest is lower by 2-5‰ than modern water δ18O at the crest of the Dinaric Alps. That unevaporated meteoric water δ18O might have been lower than today at the crest of the range suggest that the Dinaric Alps were higher in the Middle Miocene that today, assuming that coastal meteoric water δ18O was similar to today. Thus, ongoing extension within the Dinaric Alps due to slab rollback may be responsible for lowering of topography.

How to cite: Sanchez Ortiz, G., Löberbauer, M., Banerjee, P., Tomašević, N., Mandic, O., Pavelić, D., Demir, V., Sharp, Z., Meijers, M., and Rugenstein, J.: Using triple oxygen measurements of lacustrine carbonates to constrain the Miocene topography of the Dinaric Alps, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-305,, 2024.

László Rinyu, Andrea Czébely, Diána Kiss, Sándor Kele, and Marianna Túri

Carbonate clumped isotope analysis, a relatively new methodology, is still developing rapidly, that is well described by the frequency of changes in the applied methodological conventions. The extent of development is also characterized by the growing, sometimes special, nature of the application areas. Innovations, while promising, can present unforeseen challenges and sometimes brings unexpected difficulties, such as the integration of 1013 Ohm resistance in the amplification circuits of Thermo Scientific 253 Plus 10 kV Isotope Ratio Mass Spectrometer (IRMS).

The goal of this improvement was that even very small ion beams can be analyzed with the factor of 3 better signal to noise ratio, which is an important aspect from the point of view of clumped isotope analysis. Unfortunately, 1013 Ohm resistance has a significant temperature dependency, which highly influences the magnitude of the detected intensities as well as on the overall long-term stability of the measurement. The daily temperature fluctuation in summer is very significant in Hungary. Under extreme conditions, when the lab's air conditioning could not maintain the desired temperature range, the long-term Δ47 reproducibility of the system achieved an SD = 60 ppm value.

In order to reduce this effect a prototype Peltier cooling device has been installed on the surface of the detector house of our IRMS. To demonstrate the achieved accuracy, precision, and long-term stability (SD <= 30 ppm) of the modified measurement system, we present results of clumped isotope analyses of international carbonate standard samples and naturally formed travertine samples (known formation temperatures are in the range of 5-95°C) and compare them with formerly published data of two reputable laboratories from the clumped community, which use different measurement equipment:

  • ETHZ: Thermo Scientific MAT253 IRMS and Kiel IV automatic carbonate device [1]
  • MIT: Nu Perspective IRMS and NuCarb automated sample preparation unit [2]

Additionally, we offer insight into the infrastructure and analytical methodology of the clumped isotope laboratory established at ICER (ATOMKI, Debrecen, Hungary). The modification implemented and the attained long-term stability may serve as a valuable reference for other laboratories encountering similar challenges.

Keywords: carbonate clumped isotope, Peltier cooling, long-term reproducibility


[1] Bernasconi, S. M., I. A. Müller, K. D. Bergmann, et al. (2018) Reducing uncertainties in carbonate clumped isotope analysis through consistent carbonate-based standardization. Geochemistry, Geophysics, Geosystems, v. 19, 2895-2914.

[2] Anderson, N. T., J. R. Kelson, S. Kele et al. (2021) A Unified Clumped Isotope Thermometer Calibration (0.5–1,100°C) Using Carbonate-Based Standardization. Geophysical Research Letters, v. 48, e2020GL092069.

How to cite: Rinyu, L., Czébely, A., Kiss, D., Kele, S., and Túri, M.: Improving the long-term Δ47 reproducibility of the Thermo Scientific 253 Plus 10 kV IRMS using a prototype Peltier cooling device, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10068,, 2024.

Ansgar Kahmen, Meisha Holloway-Phillips, Eva Morgener, David Basler, and Daniel B. Nelson

The oxygen isotope composition of cellulose (δ18O values) has been suggested to contain information on stomatal conductance (gs) responses to rising pCO2. The extent by which pCO2 affects leaf water and cellulose δ18O values (δ18OLW and δ18OC) and the isotope processes that determine pCO2 responses of gs in δ18OLW and δ18OC are, however, unknown. We tested the effects of pCO2 on gs, δ18OLW and δ18OCin a greenhouse experiment, where six herbaceous plant species were grown under pCO2 levels ranging from 200 to 500 ppm. An increase in pCO2 caused a decline in gs. The effects of gs on δ18OLW were caused by direct and indirect mechanisms but were generally small. The model parameter effective path length (Lm) was unaffected by changes in pCO2. pCO2 effects on δ18OLW were not directly transferred to plant δ18OC but were attenuated in grasses and amplified in dicotyledonous herbs and legumes. This is likely because of functional group specific pCO2 effects on the model parameter pxpex. Our study removes critical uncertainties for using δ18OC as a proxy for gs. At the same time, our study shows that gs effects on δ18OLW and δ18OC are rather small, possibly too small to be detected in natural settings.

How to cite: Kahmen, A., Holloway-Phillips, M., Morgener, E., Basler, D., and Nelson, D. B.: Is the sensitivity of leaf water and cellulose δ18O values sufficient for detecting effects of increasing atmospheric CO2 on stomatal conductance in plants? , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14826,, 2024.

Claudia Voigt, Fernando Gázquez, Ana Isabel Sánchez-Villanueva, Lucía Martegani, Elvira Ruíz-Caballero, Jorge Cañada, and Miguel Rodríguez-Rodríguez

Triple oxygen isotopes of lacustrine gypsum and carbonate deposits are used to quantitatively assess past hydroclimate conditions. An accurate interpretation of these paleo-archives requires a fundamental understanding of processes driving the variability of 17O-excess in hydrologically different lake systems and their dynamics. Here, we present results of an ongoing monitoring study of triple oxygen and hydrogen isotopes and lake hydrology of two adjacent lakes in southern Spain, which differ in morphology, hydrogeological functioning, and water chemistry. Laguna Grande is a permanent, ∼8 m deep water body that receives groundwater discharge from the aquifer. In contrast, Laguna Chica is a temporal lake with a maximum depth of 1.5 m, which is only fed by precipitation and basin discharge and desiccates during exceptionally long periods of drought. The region is characterized by semi-arid climate and strong seasonality of precipitation. The dataset comprises three hydroperiods between 2020 and 2023. This period has been extremely dry in the South of Spain. We compare non-steady-state isotope and hydrological mass balance model results to monthly observations of lake levels and lake water isotope data to assess the mechanisms that control lake hydrology from daily to annual scale.

Laguna Grande showed significantly less isotope variability (δ18O ranged from 5.7 to 9.6‰, 17O-excess from -34 to -86 per meg, d-excess from -28 to -43‰) than Laguna Chica (δ18O ranged from -1.5 to 20.8‰, 17O-excess from -7 to -153 per meg, d-excess from -2 to -89‰). In general, 17O‑excess and d‑excess decreased with increasing δ18O, indicating the impact of evaporation. The highest δ18O and lowest 17O-excess and d-excess values occurred at the end of summer before the start of the next rainy season. Annual average δ18O of Laguna Grande increased by ∼0.7‰ per year, while 17O-excess (∼10 per meg per year) and d-excess (∼2 ‰ per year) decreased slightly. This indicates that evaporation exceeded water inflows, which is consistent with the 2 m water level drop observed over the study period. Laguna Chica showed high interannual isotope variability. In particular, the timing of desiccation determines its maximum evaporative isotope enrichment. The highest δ18O and lowest 17O-excess and d-excess were observed in October 2022, just before complete desiccation. The lake was refilled in the subsequent rainy season but dried up in May 2023 preventing it from reaching the high level of evaporation observed in the preceding hydroperiods. Changes in the length of the hydroperiod and the timing of desiccation need to be considered when interpreting isotope data of paleo-lake water obtained from lake sediment archives. The non-steady-state isotope-hydrological mass balance model agrees reasonably well with observations, showing that lake’s isotope variability can be predicted even in highly dynamic systems. However, uncertainty in the lake volume-to-surface area ratio at low water level stages challenge accurate prediction of the lake isotope composition. 


How to cite: Voigt, C., Gázquez, F., Sánchez-Villanueva, A. I., Martegani, L., Ruíz-Caballero, E., Cañada, J., and Rodríguez-Rodríguez, M.: How hydroclimate variability drives triple oxygen isotope dynamics in permanent and temporal lakes in Southern Spain, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6261,, 2024.

Reconstructing the Sahelian atmospheric relative humidity associated with vegetation changes using the 17O-excess of phytoliths from Lake Guiers sediments.
Julie Aleman, Anne Alexandre, David Au Yang, Corinne Sonzogni, Jean-Charles Mazur, Christophe Peugeot, Eric Mougin, Christine Vallet-Coulomb, Manuela Grippa, Nogmana Soumaguel, and Adama Gaye
Tao Li, Yuhua Li, Ye Tian, Erika Salas, Xiaofei Liu, and Wolfgang Wanek

Bound amino acids constitute a significant portion of soil organic nitrogen, which represents an essential source of nitrogen for plant and microbial nutrition. The analysis of the content and isotope enrichment of bound amino acids still represents a significant challenge due to the degradation of certain amino acids following the conventional acid hydrolysis method, due to the low isotope enrichment levels reached under near-native soil conditions and due to the lack of isotopically labelled standards for some key amino acids. In this study, we used both a 13C-labeled and unlabeled 16 algal amino acid mixture to establish standard calibration curves for various amino acids, using the 6-Aminoquinolyl-N-hydroxysccinimidyl carbamate (AQC) derivatization method and the ultra-high-performance liquid chromatography with high-resolution Orbitrap mass spectrometry (UPLC-Orbitrap MS) platform. Molecular ions of AQC-derivatives for all amino acids were identified at the expected m/z values of the respective isotopologues, and the isotope calibration curves exhibited excellent linearity for those amino acids where we had isotope standards at hand (polynomial R2 > 0.9896). However, the polynomial fitting terms differed between single amino acids. Subsequently, we developed equations to relate the calibrated regression terms to physicochemical properties of the respective amino acids. First, we conducted a linear regression using the Orbitrap-derived 13C atom % of unlabeled standards against the carbon atom number of the specific amino acid-AQC derivative molecules, demonstrating great linearity (R2 = 0.9728). This linear regression curve allowed us to predict the natural 13C abundance of amino acids unavailable as isotopically labelled standards (e.g. hydroxyproline, meso-diaminopimelic acid). Consequently, based on further regressions, we could ultimately develop isotope calibration curves for those amino acids unavailable as 13C labelled standards based on the integrated isotope calibration functions. This general predictive model can be applied to comprehensively and highly sensitively (13C enrichment ~0.01 at %) quantify isotope enrichments of the whole soil amino acids profile, providing valuable insights for a better understanding of the overall fate of different amino acids in soils.

How to cite: Li, T., Li, Y., Tian, Y., Salas, E., Liu, X., and Wanek, W.: Development of a comprehensive and ultrasensitive isotope calibration method for soil amino acid profiles using Orbitrap mass spectrometry, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7124,, 2024.

Gunjan Agrawal and Prasanta Sanyal

Diet-related diseases such as nutritional stress, malnutrition and eating disorders resulting from an unhealthy diet contribute to various health issues, which in some cases may be life-threatening. An accurate diet reconstruction is thus crucial for individuals at risk due to dietary concerns. The principle of diet reconstruction is rooted in the proverb ‘you are what you eat’, and an individual’s diet is the sole source of nitrogen and carbon in their body. The stable isotope composition of nitrogen (δ15N) and carbon (δ13C) can serve as a tool to recognise dietary patterns and identify health conditions. However, the variations in the values of δ15N and δ13C isotopes can imply either dietary changes or disorders associated with diet, making it challenging to ascertain the precise cause of such variations. This study aimed to establish the relationship between the isotopic composition of human tissues, specifically scalp hair and fingernails, and diet. Samples of human tissues were collected from 100 healthy participants within a 15-day period, with 74 of them providing comprehensive diet records. The participants resided in a controlled environment, a remote residential campus with limited food options and restricted access to external food sources. This controlled setting ensured that the isotopic composition of the collected samples solely reflected the impact of diet, eliminating the influence of environmental factors and dietary disorders on the isotopic composition. All the dietary sources and sixty-six food items available to the participants were considered and analysed, respectively, to determine the percentage of animal protein in their diet. This was correlated with the δ15N and δ13C values of human tissues to quantify the proportion of animal protein in diet using linear equations. The variations in the δ15N and δ13C values of human tissues resulting from dietary changes were calculated and distinguished from those caused by dietary disorders. The study results demonstrated that the amount and type of food consumed impact the δ15N and δ13C values of human tissues. An increase in animal protein intake was associated with an increase in the dual isotopic composition. Notably, the nitrogen isotope values of human tissues differed by 0.9‰ between lacto-vegetarians and omnivores. The study further revealed that a 5% dietary change resulted in fluctuation of 0.4 - 0.5‰ in both δ15N and δ13C isotope ratios. This was compared to changes caused by dietary disorders in δ15N and δ13C values of human scalp hair. These findings help in determining whether the variations in δ15N and δ13C values of human tissues result from increased animal protein intake or serve as indicators of dietary disorders.

How to cite: Agrawal, G. and Sanyal, P.: Investigating the impact of diet on the stable isotope composition of human scalp hair and fingernails, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-537,, 2024.

Sierra Grange, Johanna Girardi, Clara Mendoza-Lera, Jens Dyckmanns, Katherine Muñoz, Melanie Brunn, and Hermann Jungkunst

Exploring invasive plant species, in this case the infamous Fallopia japonica, has become pivotal in understanding their impact on biogeochemical processes within ecosystems. Building upon the work of Girardi et al., who investigated how F. japonica uses polyphenols to inhibit nitrification, our study employs stable isotope analysis to delve into the biogeochemical niche-building mechanisms of this invasive species. Following Girardi et al.’s findings, which highlighted the inhibitory effects of resveratrol on potential nitrification rates in F. japonica invaded riparian ecosystems, our research takes a step further to investigate the broader implications of the success of F. japonica. We employed stable isotopes, ¹³C-CO2 and ¹⁵N-NO3 and -NH4, to shed light upon the biogeochemical dynamics associated with the invasive prowess of F. japonica and find whether Fallopia japonica exhibits a higher affinity for ammonium than nitrate when compared to the native species Urtica dioica, and whether it allocates resources predominantly to root growth.


Contrary to previous hypotheses, our results challenge the belief that F. japonica exhibits a higher affinity for ammonium than nitrate compared to native species. Through our labelling experiments on young F. japonica and Urtica dioica (native) plants, we discovered that F. japonica displays a lower affinity for ammonium than U. dioica. Additionally, F. japonica demonstrated higher nitrogen-use efficiency and a pronounced preference for allocating resources to root biomass, underlining its ability to efficiently utilize nitrogen resources. These findings shed light on the intricate mechanisms behind the ability of F. japonica to disrupt ecosystems, emphasizing the importance of stable isotopes in unraveling such complexities. Through the integration of stable isotope probing techniques and a comprehensive understanding of rhizosphere processes, our work contributes to the ongoing efforts to foster sustainable and efficient agricultural systems in the face of global change. Moving forward, our research trajectory aims to explore the impact of phenols on nitrification in soils. Specifically, we plan to apply phenols to soil and investigate their effects on nitrification, with potential implications for denitrification processes. This endeavor aligns with the broader goal of understanding the multifaceted interactions between invasive plant species and biogeochemical processes, contributing to the development of effective strategies for invasive species management.


Keywords:                      Fallopia japonica, Urtica dioica, invasive species, native species, nitrogen cycle, nitrogen use efficiency, ammonium, 15N labelling, 13C labelling, biogeochemical niche, stable isotopes

How to cite: Grange, S., Girardi, J., Mendoza-Lera, C., Dyckmanns, J., Muñoz, K., Brunn, M., and Jungkunst, H.: Biogeochemical Niche building of Invasive Fallopia japonica: Insights from Stable Isotope Probing, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-22257,, 2024.

Mercury deposition and bioaccumulation influenced by sea ice variability in coastal Antarctic ecosystems
Yulu Xue, Guangyi Sun, Yi Liu, Ruoyu Sun, and Xiaodong Liu
Tassiane Junqueira, Daniel Ferreira-Araújo, and Bas Vriens

The Laurentian Great Lakes are a globally unique freshwater resource, playing a pivotal role in public water supply and agriculture, transportation, hydroelectric power, and ecosystem functioning. However, the Great Lakes also have a long history of metal contamination, especially in so-called Areas-of-Concern near urban areas and industrial sites. One major anthropogenic contaminant in the Great Lakes is Zn, derived from point-sources such as metal mining, smelting, and chemical industries, as well as diffuse sources such as fertilizer application or urban runoff, in addition to natural inputs from atmospheric deposition and natural weathering. Disentangling the importance of these geogenic versus anthropogenic sources and processes is critical to improving our understanding of the cycling and environmental fate of Zn in the Great Lakes region.

We examined spatiotemporal variations in Zn concentrations and isotopic compositions, as well as bulk physicochemical and mineralogical properties, of a total of 72 surface sediments and sediment core samples across nearshore-to-offshore gradients and depositional environments with distinct limnological conditions spanning >50 years.

Our results reveal spatial variations in both Zn concentrations (18 to 580 mg/kg) and isotopic compositions across oligotrophic (Lake Huron) to mesotrophic (Lake Erie) environments. Interestingly, the intra-lake heterogeneity is comparable to or higher than the variability observed at the inter-lake (basin-scale) level, with no upstream-to-downstream accumulation being evident. The isotopic signatures of surface sediment, measured as δ66Zn and ranging from -0.09‰ to +0.41‰, suggest a predominantly geogenic source for Zn. Furthermore, an examination of temporal trends in sediment cores from Lake Huron and Lake Erie indicates consistent metal concentrations and Zn isotopic signatures, implying minimal biogeochemical fractionation within the lakes themselves. Across all sediments and both lakes, metal concentrations and isotopes are positively but not very strongly (R2<0.49 overall) correlated to TOC, TN, and TP, but not to chlorophyll a.

In summary, our findings indicate that sedimentation plays a crucial role as a repository for metals in the Great Lakes, exerting significant influence on the distribution patterns of metals throughout the basin. Furthermore, the higher levels of metals at locations with historical contamination remain spatially constrained and do not seem to disrupt the interconnected system of the Great Lakes.

How to cite: Junqueira, T., Ferreira-Araújo, D., and Vriens, B.: Zinc Isotope Study of Baseline Occurrence Patterns and Potential Contamination of Sediments from the Great Lakes Basin, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1377,, 2024.

Giuseppe Caso, Maria Di Rosa, Salvatore Di Rosa, Mauro Rubino, and Fabio Marzaioli

During the last decades great attention was paid to Particulate Matter (PM) due to the correlation between fine PM exposure and adverse health effects.

  Among the airborne pollutants, Lead (Pb) is one of the most widespread and toxicologically important. Metallic Pb and inorganic Pb compounds are classified as possible carcinogenic for humans. Pb can bioaccumulate in the human body system, causing damage to human nervous system, cardiovascular diseases, reproductive impairments, and catalyzing cells oxidative stress.

  In Italy, Legislative Decree no. 155 of 13/08/2010 (implementation of European Directive 2008/50/EC) defines the atmospheric PM10, PM2.5 and airborne pollutants threshold concentration values. These threshold values are applied for anthropogenic particulates, so, the Pb source apportioning in PM can offer the key to manage the problem.

   Pb has four stable isotopes, i.e. 204Pb, 206Pb, 207Pb, and 208Pb. The isotopic ratios of Pb act as “fingerprint” that allows to identify the PM emission sources in the environment (crustal, vehicular traffic, municipal solid waste incinerator, etc …).

  The PM 2.5 and PM10 sampling will be carried out by ARPAC monitoring network, using high-volume samplers placed in Campania (Italy) environmental interest points (urban centers, busy roads…). The sampling flow is 2.36 m3/h, single sampling time is 24 hours and the use of quartz fiber filters Ø = 47mm is provided (according to the technical standard UNI EN 12341:2014).

  Precise and accurate measurement of Pb and relative isotope ratios requires a multi-step process for analysis of solid samples:

  • Microwave-assisted treatment of filters with strong acid to solubilize all the metallic species (EPA 3051 A 2007);
  • A First qualitative and quantitative measurement by Inducted Coupled Plasma Optical Emission Spectroscopy (ICP-OES) to estimate the total Pb concentration (moreover, the quali-quantitative determination of other metals is an important information for environmental purposes);
  • Lead Extraction and purification from matrix and interfering elements by ionic resins in ISO 4 clean room;
  • Mass spectrometry measurement for lead isotope analysis by High Resolution Multi-Collector Inducted Coupled Plasma Mass Spectrometry (HR-MC-ICPMS).
  • Improvement of data interpretation accuracy comparing experimental data to isotopic lead ratio values in research databases (i.e. IBERLID: lead isotope database and tool for metal provenance and ore deposits research).

  However, the identification of anthropogenic Pb sources enables to establish the origin of a portion of collected PM. So, when an overcoming of PM threshold concentration is observed, thanks to the isotopic analysis information, competent authorities can act in an efficient and successful way.

How to cite: Caso, G., Di Rosa, M., Di Rosa, S., Rubino, M., and Marzaioli, F.: Lead in particulate matter source apportioning by HR-MC-ICPMS stable isotope ratio measurements, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6355,, 2024.

Wenhao Wang, Vladislav Chrastný, Johannes Hettler, Naresh Kumar, and Stephan Kraemer

Chromium (Cr) is a redox sensitive element and Cr isotope composition (δ53Cr) has been widely utilised to reflect the extent of Cr(VI) reduction during Cr pollution mitigation, as well as changes in past atmospheric/oceanic oxygenation. Whilst redox transformations are thought to primarily drive the Cr isotopic variability in modern aquatic environments, other processes, such as ligand promoted dissolution, can occur, potentially overprinting the intrinsic δ53Cr signal.

In this study, laboratory-controlled batch and flow-through column experiments on two distinct soil materials were conducted to understand the leaching behaviour of Cr and Cr isotopes, under both oxygenated and O2-free conditions. Significant dissolution of Cr(III), together with Fe and Mn, from the solid phase in the presence of low-molecular-weight organic acids was observed over the time course of all experiments. Initial isotope analyses on Cr(III)-citrate complexes show that δ53Cr values are ~ −0.60 to −0.09‰, reflecting the pristine Cr isotopic signature of the two soil materials. In addition, whilst formation of authigenic Fe particles means that a fraction of dissolved Cr is scavenged, such that solid phase Cr may be associated with Fe, Cr does not seem to be remobilised during reductive dissolution of Fe (and Mn) oxides in these experiments.

Results from this study have several implications. Firstly, as Cr is a known carcinogen, increased levels of organic ligands, e.g., in paddy field systems, can cause increased environmental and health risks. Secondly, organic ligands may play an overlooked role in modulating the input and removal processes of dissolved Cr to/from various environments. Finally, ligand-bound Cr(III) likely has a ‘stabilised’ isotopic signature that is distinct from Cr(VI), making it possible to trace this ‘additional’ Cr in aquatic systems; it is difficult to characterise or quantify these Cr-organic complexes using conventional analytical methods.

This work is part of the CHROMA project funded by H2020-MSCA-IF (101031974).

How to cite: Wang, W., Chrastný, V., Hettler, J., Kumar, N., and Kraemer, S.: Isotope fingerprinting of organically complexed chromium – the natural story of a pollutant, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18111,, 2024.