Dear colleagues,
Last Monday I have sent around a question about the identification of
a (for me) unknown pollen type that was present in a pollen slide from
a Medieval site in the Netherlands.
My request was successful: Suzanne Leroy recognised Nitraria
(Zygophyllaceae). Frank Schlütz also recognized Nitraria and he
suggested me to ask my colleague Carina Hoorn to show me a reference
slide of modern Nitraria. And then it appeared that a modern (dried)
Nitraria flower from east Asia had been processed at our lab in
Amsterdam in the same sample series as the Medieval samples.
Conclusion: this is an example of contamination. When putting the dry
recent material in a beaker, some pollen grains must have come in the
air and fell down in a beaker with the Medieval sediment sample.
Years ago we had two different rooms for the preparation of pollen
slides (modern and fossil). Nowadays we do not have that second
preparation room any more, but with this Nitraria-contamination we
have learned our lesson: in the future we will never combine the
preparation of pollen from dried flowers with the processing of
sediment samples.
best wishes,
Bas van Geel
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Dr Bas van Geel
E-mail: [log in to unmask] Phone: +31 20 525 7664 Fax: +31 20
525 7832
http://home.medewerker.uva.nl/b.vangeel/
Institute for Biodiversity and Ecosystem Dynamics (IBED)
http://www.science.uva.nl/ibed
Research Group Paleoecology and Landscape Ecology
Faculty of Science, Universiteit van Amsterdam
Visiting address: Science Park 904, 1098 XH Amsterdam
Postal address: P.O. Box 94248, 1090 GE Amsterdam, The Netherlands
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