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New stalagmites from Qadisha Cave (Lebanon) located at 1720 m above sea level provide a high-resolution and well-dated record for northern Mount Lebanon. The stalagmites grew discontinuously from 9.2 to 5.7 and at 3.5 ka, and they show a tendency to move from a more negative oxygen isotope signal at ~9.1 ka to a more positive signal at ~5.8 ka. Such a trend reflects a change from a wetter to a drier climate at high altitudes. The δ13C signal shows rapid shifts throughout the record and a decreasing trend toward more negative values in the mid-Holocene, suggesting enhanced soil activity. In the short-term trend, Qadisha stalagmites record rapid dry/wet changes on centennial scales, with a tendency to more rapid dry events toward the mid-Holocene. Such changes are characterized by overall good agreement between both geochemical proxies and stalagmite growth and might be affected by the seasonal variations in snow cover. The Qadisha record is in good agreement with other Levantine records, showing more humid conditions from 9 to 7 ka. After 7 ka, a drier climate seems to affect sites at both low- and high-altitude areas. The Qadisha record reflects uniquely mountainous climate characteristics compared with other records, specifically the effect of snow cover and its duration regulating the effective infiltration.

In the context of combined raw material and energy production, public attention focusses increasingly on geothermal power plants. The Upper Rhine Graben (URG) in southwest Germany and eastern France is of special interest as it represents a possible geothermal reservoir with raw material potential. From around 1300 different oil as well as geothermal wells and thermal water wells, knowledge can be acquired about the reservoir rocks of different depths. In the URG, the Triassic sandstones and Variscan crystalline rocks have the greatest geothermal potential. Furthermore, from these wells, the geochemical properties of the fluids can be studied and related to the reservoir rocks. Up to now, only limited knowledge is available about the recent fluid-rock interactions releasing trace elements to the fluid. There are several hypotheses about the reaction kinetics and transport mechanisms of the elements and water. One of the hypotheses is that trace elements are released by the alteration of feldspars and mica of the Variscan crystalline basement. To corroborate the hypothesis, initial mineralogical and geochemical analyses were carried out on partially altered monzogranite core samples which were extracted from different depths while constructing the geothermal power plant in Soultz-sous-Forêts (France). The first results of geochemical and mineralogic analysis revealed a need to concretize the hypothesis. Based on the direct comparison between the unaltered mineral and the alteration product, it was determined that trace elements are released but can also be fixed. Thus, the question arises whether these alteration processes lead to the present fluid composition.

Lithium is one of the critical elements for the realization of electric mobility and energy transition. With a contribution to global Li-production and recycling of less than 1% (2017), Europe depends almost entirely on Li-import. To reduce the dependency, new and unconventional Li resources are explored in the EU. One resource are highly saline brines from geothermal reservoirs of the Upper Rhine Graben (URG), characterized by Li concentrations of up to 200 mg/L. Due to space restrictions, conventional production methods are not suitable and technologies for the direct lithium extraction (DLE), such as Li-Mn oxide sorbents, is needed. Lithium-Mn oxide sorbents have a comparably high Li adsorption capacity and due to ion-sieve properties a high selectivity for Li. Batch experiments with synthetic Li+-solutions and natural geothermal brines were conducted to investigate the sorption capacity and kinetics, and the role of competing ions on Li sorption. The batch experiments reveal fast sorption kinetics with an adsorption of >70% of the maximum Li sorption capacity within several minutes. In relation to Li+-solutions, Li sorption decreases for geothermal brines due to sorption of competing ions. While alkaline metals show a relatively little influence, Mn and Ba are the major competing ions. We prove successfully that Li-extraction from geothermal brines in the URG by Li-Mn oxide sorbents is technologically feasible at the laboratory scale. Upscaling into a pilot plant integrated into a power plant is in progress.

Continuously improving ICP-MS and IRMS techniques steadily allow smaller sample sizes, higher spatial resolution and the investigation of unconventional isotopes or isotopologues (e.g., ∆48 in carbonates and CO2). These technical advances pose new challenges in sample preparation, handling, analytical procedures, data evaluation and upscaling. We welcome all contributions that address novel aspects in the use of ICP-MS or IRMS systems, e.g., unconventional isotope systems, high-resolution studies, or the quest for high precision and accuracy, but are not limited to those examples.

Lithium is an important compound in several industrial applications and is mostly found in lithium ion batteries (LIBs), ceramics and glass. Lithium deposits are hosted in pegmatites, sedimentary rocks and brines (i.e., salt lakes, salars, oilfield brines, and geothermal brines) comprising 25 - 26 %, 8 % and 59 - 66% of the world’s Li resources, respectively. Geothermal brines in the Upper Rhine Graben, Germany, with Li concentrations of up to 200 mg/L and resources of 2.7 Mt Li2CO3 represent potentially economically mineable Li deposits. The scope of our project is to extract Li from these high saline (i.e., TDS ~100 - 200 g/L) geothermal brines by sorption using natural and synthetic zeolite and clay minerals. These high saline brines are slightly acidic in pH and characterized by high concentrations of major cations (e.g., Na+ up to 60 g/L, K+ up to 4 g/L, Ca2+ up to 11 g/L and Mg2+ up to 1.9 g/L) and anions (e.g., Cl- up to 120 g/L and SO42- up to 1.5 g/L). Synthetic zeolite 13X and natural clinoptilolite-mordenite-montmorillonite mixtures have been used for preliminary sorption experiments. We performed batch sorption experiments with synthetic Li-solutions and variable concentrations and temperatures between 25 – 60 °C. Furthermore, we studied the effect of competing ions (e.g., Na+) on Li-sorption. Thereby, we investigate the different materials for sorption capacity and kinetics, chemical stability, structural effects of Li incorporation and their applicability to geothermal brines.

High-resolution speleothem paleoclimate records with annual to seasonal resolution are helpful for detailed analysis of climatic changes with limited duration (e.g., volcanic climate impacts), but also for longer-duration events (e.g., at 8.2 ka or 4.2 ka). A high resolution paleoclimate data set is also mandatory for meaningful comparison with archaeological or historical records. Low stalagmite growth rates could impede the acquisition of high-resolution isotope data with the classical micro-milling approach and isotope ratio mass spectrometry (IRMS) analysis. We therefore compared secondary ionization mass spectrometry (SIMS) stable isotope measurements at 7-15 µm resolution with the lower-resolution micro-milling results at 90 µm steps. For the investigated stalagmite from Kleine Teufelshöhle (Frankonia, Germany) the SIMS resolution corresponds to annual resolution, whereas IRMS only reaches a 4-13 year resolution. Albeit a constant offset, SIMS and IRMS δ18O data match very well (r = 0.61, p < 0.001, n = 84). This significant correspondence suggests that SIMS stable isotope analysis could be a promising alternative for high-resolution carbonate studies. An adjacent second δ18O SIMS profile reproduced high-resolution features (r=0.59, p < 0.001, n = 982) and allows a detailed assessment of paleoclimate variability on an annual scale and a comparison with independent climate records, e.g., weather information from historical documents or tree rings. Stalagmite δ18O trends closely follow the low-frequency fluctuations of a regional tree-ring record (Land et al., 2019), additionally constraining the stalagmite chronology. The different climate sensitivities of both records enable a more robust and detailed discussion of paleoclimatic variations.