Exploring the potential of d18O and d13C in pollen for reconstruction of Quaternary palaeo-climate: Pilot study towards a comprehensive calibration of stable isotopes in modern pollen from selected European plant taxa.
Mineralogy, Petrology and Geochemistry
Final Report Abstract
The potential of pollen isotopes for palaeo-climate research has not yet been explored in some depth. The aim of establishing a new archive which may provide palaeo-environmental signals in sub-seasonal resolution can possibly be reached but requires intensive fundamental research. Adding to the few existing studies, we conducted a comprehensive calibration study of modern tree pollen across Europe in order to obtain species-specific stable isotope data in different geographic and climatic settings as a fundament for environmental correlations. Interspecific, intra-specific, intra-individual and inter-annual variation of pollen isotope values can be demonstrated. The technical progress in the accuracy of mass spectrometers which allows to produce reliable pollen-δ18O and pollen-δ13C of small amounts of pollen or even single grains is not unambiguous. Our pilot study exhibits a range of several per mill in pollenδ18O and pollen-δ13C of a single tree and only analysis of large pollen amounts provides sufficient accuracy (mean values) in climate reconstructions. Our study shows e.g. that pollen stable isotopes of the conifers Pinus sylvestris and Picea abies exhibit sensitivity to local/regional environmental parameters but with a significant offset. Thus, pollen bulk samples comprising both species are not suitable to reconstruct palaeo-climate. This underpins the necessity to separate characteristic pollen morpho-types at the “species” level. We conducted different biochemical and physical experiments for separating pollen types in an efficient way. A final protocol could not yet been developed but tests with a Beckton Dickinson flow cytometer were promising and initially successful. We expect that the upcoming publications will trigger corresponding studies of other teams which we consider very positive as the need for fundamental research is huge and only international competitive collaboration will lead this avenue of research to success.
Publications
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Inter- and intra-tree variability of carbon and oxygen stable isotope ratios of modern pollen from nine European tree species. PLoS ONE, Vol. 15. 2020, Issue 6: e0234315.
Carolina Müller, Manja Hethke, Frank Riedel, Gerhard Helle
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Quantifying the impact of chemicals on stable carbon and oxygen isotope values of raw pollen. Journal of Quaternary Science, Vol. 36 2021, Issue 3, pp. 441-449.
Müller C., Hennig J., Riedel F., Helle G.
