Structural Characterization of Charcoal Exposed to High and Low Ph: Implications for 14C Sample Preparation and Charcoal Preservation
Open accessAbstract
Chemical and structural similarities between poorly preserved charcoal and its contaminants, as well as low radiocarbon concentrations in old samples, complicate 14 C age determinations. Here, we characterize 4 fossil charcoal samples from the late Middle Paleolithic and early Upper Paleolithic strata of Kebara Cave, Israel, with respect to the structural and chemical changes that occur when they are subjected to the acid-base-acid (ABA) treatment. Differential thermal analysis and TEM show that acid treatment disrupts the structure, whereas alkali treatment results in the reformation of molecular aggregates. The major changes are ascribed to the formation of salt bridges at high pH and the disruption of the graphite-like crystallites at low pH. Weight losses during the treatments are consistently greater for older samples, implying that they are less well preserved. Based on the changes observed in vitro due to pH fluctuations, various methods for removing contamination, as well as a mechanism for preferential preservation of charcoal in nature, are proposed.
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Charred seeds were pretreated with an acid-base-acid (ABA) procedure to remove all contaminants, following the methods of Yizhaq et al. (2005) and Rebollo et al. (2008).
“Charred seeds were pretreated with an acid-base-acid (ABA) procedure to remove all the contaminants, following the methods of Yizhaq et al. (2005) and Rebollo et al. (2008).”
From Absolute Chronology of Megiddo, Israel, in the Late Bronze and Iron Ages: High-Resolution Radiocarbon Dating (2014) · cites this paper as Rebollo et al. (2008)
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Radiocarbon Dating of “Old” Charcoal Using a Wet Oxidation, Stepped-Combustion Procedure
Bird, M. I., Ayliffe, L. K., Fifield, L. K., Turney, C. S. M., Cresswell, R. G., Barrows, T. T., & David, B. (1999) · Radiocarbon · doi:10.1017/s0033822200019482 · Cited by 320 · cited 1× · see citing works
“Bird et al. (1999) introduced the use of wet oxidation as the last step of the chemical pretreatment in charcoal (ABOX).”
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Toffolo, M. B., Arie, E., Martin, M. A. S., Boaretto, E., & Finkelstein, I. (2014) · Radiocarbon · doi:10.2458/56.16899 · Cited by 141 · see citing works
Self-citationBoaretto, E., Finkelstein, I., & Shahack-Gross, R. (2010) · Radiocarbon · doi:10.1017/s0033822200044982 · Cited by 50 · see citing works
Self-citationAsscher, Y., Cabanes, D., Hitchcock, L. A., Maeir, A. M., Weiner, S., & Boaretto, E. (2015) · Radiocarbon · doi:10.2458/azu_rc.57.18391 · Cited by 31 · see citing works
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- Authors
- Rebollo, N. R., Cohen-Ofri, I., Popovitz-Biro, R., Bar-Yosef, O., Meignen, L., Goldberg, P., Weiner, S., & Boaretto, E.
- Affiliations
- Weizmann Institute of Science (IL)
- Harvard University (US)
- Centre National de la Recherche Scientifique (FR)
- Boston University (US)
- Bar-Ilan University (IL)
- Corresponding author
- Boaretto, E
- Venue
- Radiocarbon
- Publisher
- Cambridge University Press (CUP)
- Published
- 2008
- Volume
- 50
- Issue
- 2
- Pages
- 289-307
- ISSN
- 0033-8222 (ISSN-L)
- 1945-5755
- OpenAlex
- W2124329325
- Cited by
- 82
- References
- 1
- Citations by year
- 2025: 2 · 2024: 4 · 2023: 3 · 2022: 2 · 2021: 5 · 2020: 7 · 2019: 6 · 2018: 8 · 2017: 6 · 2016: 5 · 2015: 4 · 2014: 7 · 2013: 7 · 2012: 5
- FWCI
- 2.52
- Type
- journal article
- Language
- en
- Open access
- green
- nrs.harvard.edu
- Locations
- Radiocarbon (publishedVersion)
- UA Campus Repository (The University of Arizona) (acceptedVersion)
- Digital Access to Scholarship at Harvard (DASH) (Harvard University) (submittedVersion, cc-by)
- HAL (submittedVersion)
- Topics
- Physical Sciences › Earth and Planetary Sciences › Paleontology › Archaeology and ancient environmental studies
- Physical Sciences › Materials Science › Materials Chemistry › Graphite, nuclear technology, radiation studies
- Social Sciences › Arts and Humanities › Archeology › Cultural Heritage Materials Analysis
- Keywords
- fossil charcoal, salt bridges, graphite crystallites, Middle Palaeolithic, Upper Palaeolithic, Kebara Cave, differential thermal analysis, transmission electron microscopy
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