2024
July 2024 | TED talk by Prof Nicolas Waldmann
Prof Nicolas Waldmann gave a TED talk as part of the ambassadors program of the university. The talk was 5 minutes long and was on climate warming. The ambassadors program aim to enlarge the scientific, educational and financial possibilities at the university by increasing fundraising. It was a very intensive course program, with several steps and actions that culminated with the TED event in front of the whole university.
ניקולס.mp4June 2024 | Parth Shah defended his PhD thesis!
Congrats to Dr Parth Shah who just defended his PhD thesis! Parth's thesis deals with past climate and environmental reconstruction as retrieved from a multidisciplinary study of sediments cores from two lakes in southern Arabian Peninsula. The results of his study were published in several papers and he is currently working on more publications. Stay tuned for more updates coming out of his research!
May 2024 | Mfoniso presented his results at the Geological Society of Israel annual meeting
Mfoniso Anieti went to Jerusalem to present the results from his MSc research at the GSI meeting. His project deals with paleomagnetic data from Lake Fagnano in Tierrad del Fuego (southernmost South America). His poster was very well attended by colleagues from several universities in Israel.
Well done, Mfoniso!
April 2024 | Parth Shah gave a talk at CSD, University of Minnesota!
Parth Shah gave an excellent talk on the results of his PhD thesis at the University of Minnesota's CSD facility. Parth got a scholarship for visiting CSD facility for sampling more lake sediments as part of his research. CSD personnel invited him to give a talk. So, congrats Parth!
March 2024 | New paper with Petrolabers in Biogeosciences!
A new paper just came out in Biogeoscience. In this work, the reliability of long-term climate signals registered in the sediments of Lake Chala by comparing downcore variations in GDGT distributions with major phases in lake-system evolution were assessed. The record suggest that during early lake history (ca. 180–200 ka) the distinct mixing-related depth zones with which specific GDGT producers are associated in the modern-day lake were not yet formed, likely due the absence of chemical water-column stratification. Consequently absolute GDGT concentrations dating to this period are relatively low, proxies sensitive to water-column stratification (e.g., branched versus isoprenoid tetraether (BIT) index) display highly irregular temporal variability, and correlations between proxies are dissimilar to expectations based on modern-system understanding. A sequence of lake-system changes between ca. 180–200 and ca. 80 ka first established and then strengthened the chemical density gradient, promoting meromictic conditions despite the overall decrease in lake depth due to the basin gradually being filled up with sediments. From ca. 180 ka onward some GDGTs and derived proxies display strong ∼ 23 kyr periodicity (precession-driven insolation). Our results suggest that GDGT-based temperature and moisture-balance proxies in Lake Chala sediments reflect the climate history of eastern equatorial Africa from at least ca. 160 ka onwards. This work confirms the potential of lacustrine GDGTs for elucidating the climate history of tropical regions at Quaternary timescales, provided they are applied to suitably high-quality sediment archives. Additionally, their interpretation should incorporate a broader understanding of the extent to which lake-system evolution limits the extrapolation back in time of proxy-climate relationships established in the modern system.
February 2024 | New paper just came out of the oven from PetroLab!
A new paper just came out in Journal of Paleolimnology. In this work, we disentangled alteration processes occurring at the redox front below the sediment–water interface of a ventilated deep-water lake (Lago Fagnano, Argentina/Chile). A sequential extraction protocol was applied to characterize two reactive Fe pools: Fe oxyhydroxides and reduced iron. Subsequently, Fe isotopes were constrained to determine the main processes mobilizing Fe. At the redox front, ferric minerals reach a δ56Fe value of − 1.3‰ resulting from oxidation of dissolved Fe likely following a Rayleigh distillation effect. Dissolved Fe is produced right below via Fe reduction, as shown by the low ferric Fe content. Our observations delineate a redox cycle and a redox horizon undergoing constant upward migration, initiated by regular sedimentation. However, during events of increased rapid sedimentation (e.g., seismites) this dynamic cycle is interrupted inducing full or partial preservation of the Fe-rich redox front. In such case, oxidation of dissolved Fe is interrupted and can be recycled in ferrous minerals, such as Fe monosulfides and amorphous phases with δ56Fe values down to − 1.7 ‰. These findings have significant implications for the recording of biogeochemical cycles in the geological past, the use of Fe isotopes in freshwater-lake sediments for paleoclimate studies, and the progress of our knowledge regarding the geochemistry of past oceans.
