Hydrogen isotope fractionation in ammonia-oxidizing archaea

In recent years, the potential of the hydrogen stable isotope composition (δ2H) signature of isoprenoid glycerol dibiphytanyl glycerol tetraether (GDGT) membrane lipids of ammonia-oxidizing archaea (class Nitrososphaeria) as a novel palaeohydrological proxy has gained increasing attention. This PhD thesis investigates the hydrogen isotope fractionation (2εL/W) in Nitrososphaeria to assess the suitability of δ2H of GDGT-derived biphytanes (BP), particularly of BPcren derived from crenarchaeol (δ2HBPcren), as a palaeohydrological proxy. Therefore, the species-dependent variability of 2εL/W among four different species of Nitrososphaeria (Nitrosopumilus maritimus, Nitrosopumilus adriaticus, Nitrosarchaeum koreense and Nitrososphaera viennensis), the relationship between δ2H of the growth water (δ2HH2O) and δ2HBPcren, and the variability of 2εL/W depending on temperature, pH and salinity were investigated. The results indicate that Nitrososphaeria exhibit a narrow range of 2εL/W (BPcren: -257‰ to -307‰) at optimal growth conditions. Despite the interspecies variability in 2εL/W, δ2HBPcren correlates linearly with δ2HH2O in both marine and soil Nitrososphaeria, providing a first calibration for palaeohydrological reconstructions based on δ2HBPcren. All investigated species exhibit a negative correlation between 2εL/W of the biphytanes and growth temperature, with the exception of BP0 and BP1 in N. viennensis. However, the rates of temperature-dependent 2εL/W-change can differ substantially depending on the species. In N. maritimus, an increase of 2εL/W was observed for all biphytanes with increasing salinity. The observed isotopic fractionation is likely caused primarily by changes in the size and/or turnover rates of the intracellular water pool or NADPH pool, influencing recycling rates and thereby affecting the enrichment of 2H in the intracellular water pool and NADPH pool. The relationship between 2εL/W and pH remains unresolved, as N. maritimus and N. viennensis exhibit different responses to pH changes. The comparatively limited variability of 2εL/W observed in Nitrososphaeria, supports the potential applicability of δ2HBPcren as a paleohydrological proxy.

Level thesis:degree_level

thesis.doctoral

Grantor dc:publisher

Christian-Albrechts-Universität zu Kiel

Year

2026

Author dc:creator

• Rosendahl, Chris Daniel

Contributors dc:contributor

• Elling, Felix
• Kulhanek, Denise Kay

• hydrogen stable isotopes
• GDGTs
• Nitrososphaeria
• paleohydrology
• crenarchaeol

Repository record source_url

https://macau.uni-kiel.de/receive/macau_mods_00008778

OAI identifier oai:identifier

oai:macau.uni-kiel.de:macau_mods_00008778