Opaline phytoliths are important microfossils used in archaeological and ecological research. Relatively little is known about the stability of phytoliths after burial. Under alkaline pH conditions they can dissolve, and mechanical disturbances can cause a loss of their more delicate appendages. Here we present an experimental study of phytolith stability (combination of solubility and abrasion). Modern and fossil phytoliths were extracted from wheat using new methods to minimize dissolution, and by burning in an oven. These assemblages were placed in a solution buffered to pH 10 and maintained under constant temperature and shaking conditions. The silicon concentrations in the solution were monitored once a week for 5 weeks. The phytolith morphologies in each assemblage were determined at the outset of the experiment and after 5 weeks. The results show that there are differences in stability between various assemblages. Modern inflorescence wheat phytolith assemblages are more unstable than those from leaves/stems. Burnt assemblages are less stable than unburnt assemblages, and a fossil phytolith assemblage about 3000 years old is more stable than the modern wheat assemblages. The results also show that individual phytolith morphotypes have different stabilities, and as a result of dissolution and abrasion, some morphotypes may resemble others. This study further shows that archaeological and/or paleo-environmental interpretation of phytolith assemblages may change with the assemblage's state of preservation.
Bibliographical noteFunding Information:
We would like to thank Yotam Asscher for his help during the development of the fossil phytolith extraction system and Dr. Elisabetta Boaretto for helpful comments. We also thank Profs Ayellet Gilboa and Ilan Sharon for the sample from Tel Dor. The research leading to these results was funded by the European Research Council under the European Community’s Seventh Framework Programme (FP7/2007-2013)/ERC grant agreement n° 229418 . D.C. postdoctoral fellowship is also funded by the Beatriu de Pinós program (Departament d’Universitats, Recerca i Societat de la Informació de la Generalitat de Catalunya). The authors are members of the Research Group for Palaecological and Geoarchaeological Studies (GEPEG).
- Alkaline pH
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