Determination of isotope composition in archaeological charred grains

0583760 - ARÚB 2024 CZ eng A - Abstrakt
Pernicová, Natálie - Apiar, Jana - Čáslavský, Josef - Trnka, Miroslav - Urban, Otmar
Determination of isotope composition in archaeological charred grains.
Quo Vaditis Agriculture, Forestry and Society under Global Change? From understanding past and present Earth´s processes to adaptations for the future. Brno: Ústav výzkumu globální změny AV ČR, v. v. i., 2022 - (Šprtová, M.; Bartošová, L.; Acosta, M.; Klem, K.; Leventon, J.; Červený, J.). s. 22. ISBN 978-80-87902-36-3.
[2nd international scientific conference Quo Vaditis Agriculture, Forestry and Society under Global Change? 19.09.2022-21.09.2022, Velké Karlovice]
Institucionální podpora: RVO:68081758
Klíčová slova: isotopes * archaeological charred grains * experiment * past climate
Obor OECD: Archaeology
https://www.czechglobe.cz/wp-content/uploads/2022/09/Book-of-Abstracts.pdf

The isotopic composition of plants reflects the environmental conditions during the growth (temperature, precipitations) as well as the physiological ability of plants to cope with such an environment (e.g., adjustment of water use efficiency). Therefore, stable isotopes represent an important proxy data of past climate and are often used in paleoclimatic or archaeological research. The crop remains retrieved from archaeological sites are often preserved by charring. However, the effects of charring on the composition of stable isotopes and thus the interpretation of isotopic signals are not fully understood.This experiment aimed to determine the representation of stable isotopes in artificially carbonized grains and compare these to isotopic signals from archaeological grains. We focus on the following questions: What is the effect of charring on elemental contents (C, N, O) and their isotope abundances? Are there any shifts in signals due to the charring process? We have used grains of ancient wheat cultivars (einkorn and emmer) and precisely documented archaeological (charred) samples. The grains were carbonised in a muffle furnace at two temperatures (250 and 300 °C) and two atmospheric conditions (aerobic and anaerobic). While the grains were left free on the Petri dish to achieve aerobic conditions (O2 of ca. 21%), these were inserted in the sand and wrapped in aluminium foil to achieve anaerobic conditions (O2 less than 2%). All samples were heated for 2, 4, 8, 16 and 24 hours. After that, samples were homogenized and weighted (approximately 1.5 mg). Isotope ratios were measured using the elemental analyser (varioPYRO cube) coupled to a continual flow isotope ratio mass spectrometer. The morphology of grains exposed to anaerobic conditions at 300 °C for 16 and 24 hours was similar to those from archaeological findings. All elements/isotopes tested were detectable in artificially charred grains as well as in the archaeological remains, including nitrogen.
Trvalý link: https://hdl.handle.net/11104/0352214