On Monday 27th September 2021 14:00 CEST we will have one of our almost regular quasi-monthly ECOFUN meetings open to our friends, colleagues and collaborators. These meetings aim to provide a friendly, safe and relaxed space for early career researchers to present the research they are working on, to ask questions and to obtain useful feedback and support from our community.

We are delighted that Claudia Voigt from CEREGE in Marseille will present some results from her latest research.

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The title of her talk will be:

The triple oxygen isotope composition of leaf water and phytoliths: Insights for a new proxy of continental atmospheric humidity

ABSTRACT: Recently, growth chamber experiments and natural transect calibrations showed the potential of the triple oxygen isotope composition of phytoliths, expressed by 17O‑excess, as a quantitative proxy for past changes in relative humidity. The isotope composition of phytoliths reflects the isotope composition of leaf water, which is mainly controlled by evaporative fractionation, and mostly responds to relative humidity. However, although models usually correctly depict the main trends of the leaf water when relative humidity decreases, the calculated isotope values often depart from the observed ones.

I will present a 24-hour record of δ17O, δ18O, δ2H, 17O-excess and d-excess of F. arundinacea leaf water. The grass was grown under natural climate conditions in a regularly irrigated 2×2 m plot at the O3HP oak observatory (Mediterranean area, France). Climate and plant physiological parameters as well as the isotope composition of the irrigation water and atmospheric water vapor were monitored. The relative humidity varied between 40 and 100 % over the experimental period, leading to variability in δ18O, 17O‑excess and d‑excess of the grass leaves from 2.1 to 10.5 ‰, from –32 to –151 per meg, and –27 to –87 ‰, respectively. The leaf water isotope data will be compared to results obtained from isotope modelling based on the classic Craig-Gordon evaporation model. The combination of hydrogen and triple oxygen isotope analyses of leaf water may help to improve the understanding of processes that drive changes in the leaf water’s isotope composition, and thus, contribute to a better understanding of the phytolith isotope signature.

Look forward to catching up with everybody.

Please contact lisa.wingate@inrae.fr if you wish to attend this zoom meeting.

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