TY - JOUR
T1 - Trace element ratios in tooth enamel as palaeodietary indicators of seaweed consumption and coastal grazing, and their broader applicability
AU - Blanz, Magdalena
AU - Stewart, Samuel
AU - Mainland, Ingrid
AU - Ascough, Philippa
AU - Raab, Andrea
AU - Feldmann, Jörg
AU - Taggart, Mark A.
N1 - Funding Information:
This research was funded by the European Social Fund and Scottish Funding Council as part of the Developing Scotland's Workforce in the Scotland 2014–2020 European Structural and Investment Fund Programme. Modern samples were made available from previous research funded by a UK Natural Environment Research Council grant (NERC; NER/B/S/2003/00223 ). Additional samples were made available by Steve Dockrill and Julie Bond (Swandro), Orkney Museum and Gail Drinkall (Beachview), Nick Card and Jane Downes (Ness of Brodgar and Mine Howe) and David Griffiths (Snusgar). The authors would like to thank Marie Balasse and Denis Fiorillo for enabling the analysis of δ 13 C and δ 18 O of the tooth enamel samples at SSMIM (MNHN) Paris. Analysis of bone collagen was performed at the Scottish Universities Environmental Research Centre and made possible through a British Academy Mid-Career Fellowship (2014-5) for IM. MP-AES and ICP-MS analyses of the tooth enamel were performed at TESLA, Aberdeen, and ICP-OES analyses of vegetation, soil and sand at ERI, Thurso. The farmers who provided the modern sheep mandibles and/or information on sheep herding practices in the Orkney archipelago are also gratefully acknowledged: Robert Mainland on Rousay, Kevin Woodbridge, Billy Muir and the North Ronaldsay sheep court on North Ronaldsay, and Linda Hagan on Holm of Aikerness. Benjamin Blanz’ kind support on the use of R software is also gratefully acknowledged.
Funding Information:
This research was funded by the European Social Fund and Scottish Funding Council as part of the Developing Scotland's Workforce in the Scotland 2014?2020 European Structural and Investment Fund Programme. Modern samples were made available from previous research funded by a UK Natural Environment Research Council grant (NERC; NER/B/S/2003/00223). Additional samples were made available by Steve Dockrill and Julie Bond (Swandro), Orkney Museum and Gail Drinkall (Beachview), Nick Card and Jane Downes (Ness of Brodgar and Mine Howe) and David Griffiths (Snusgar). The authors would like to thank Marie Balasse and Denis Fiorillo for enabling the analysis of ?13C and ?18O of the tooth enamel samples at SSMIM (MNHN) Paris. Analysis of bone collagen was performed at the Scottish Universities Environmental Research Centre and made possible through a British Academy Mid-Career Fellowship (2014-5) for IM. MP-AES and ICP-MS analyses of the tooth enamel were performed at TESLA, Aberdeen, and ICP-OES analyses of vegetation, soil and sand at ERI, Thurso. The farmers who provided the modern sheep mandibles and/or information on sheep herding practices in the Orkney archipelago are also gratefully acknowledged: Robert Mainland on Rousay, Kevin Woodbridge, Billy Muir and the North Ronaldsay sheep court on North Ronaldsay, and Linda Hagan on Holm of Aikerness. Benjamin Blanz? kind support on the use of R software is also gratefully acknowledged.
Publisher Copyright:
© 2022 The Authors
Copyright:
Copyright 2022 Elsevier B.V., All rights reserved.
PY - 2022/2/1
Y1 - 2022/2/1
N2 - Ratios of barium and strontium concentrations in skeletal samples (e.g. in the logarithmic form lg(Ba/Sr)), are a possible alternative or supplementary marker to stable carbon isotope ratios (δ13C) for identification of marine food consumption. Previous studies have compared lg(Ba/Sr) values between different species of animals with differing diets, but few studies have been performed where animals of the same species consumed known diets ranging from completely terrestrial to completely marine. Additionally, how seaweed consumption affects dental and bone Ba, Sr and other trace element concentrations has not yet been directly investigated. In this study, tooth enamel from modern sheep (n = 15) that consumed known diets containing varying amounts of terrestrial grasses and seaweeds were analysed for their Sr, Ba, Ca, V, Mn, Co, Ni, As, and U concentrations. Additionally, δ13C values were analysed to enable comparison of δ13C and trace element ratios as markers of marine plant food consumption. The consumed vegetation types (grasses and seaweeds) were also analysed for trace element ratios, as were soils and sands from areas where the animals were pastured. To investigate how decay processes (i.e., diagenesis) may affect lg(Ba/Sr) in archaeological tooth enamel, teeth of 22 sheep from seven archaeological sites (ranging from ca. 5000 to 1000 years old) on the Orkney Islands, Scotland, were also analysed. The results show that tooth enamel from seaweed-eating sheep had significantly different lg(Ba/Sr) (−2.4 to −1.6) and δ13C values (−6.7‰ to −3.3‰) when compared to terrestrial-feeding sheep (lg(Ba/Sr) 0.6 to −0.5; δ13C −15.5‰ to −14.7‰), with a linear correlation between lg(Ba/Sr) and δ13C (R2 = 0.94). Vegetation, soil and sand results confirmed the assumed dependence of enamel lg(Ba/Sr) values on the (bioaccessible) Ba and Sr concentrations of the consumed matter. The archaeological samples had elevated relative amounts of U, V, As, Mn, Co, and Ni, attributable to diagenesis. However, the lg(Ba/Sr) values of the archaeological enamel followed the trend established using the modern samples, indicating that diagenesis did not cause significant changes in lg(Ba/Sr) in these samples. In conclusion, lg(Ba/Sr) values in enamel appear to be a useful indicator of the relative amount of marine food consumed, including seaweeds. This may be particularly advantageous for samples and locations where δ13C is unreliable or ambiguous as an indicator of marine food consumption.
AB - Ratios of barium and strontium concentrations in skeletal samples (e.g. in the logarithmic form lg(Ba/Sr)), are a possible alternative or supplementary marker to stable carbon isotope ratios (δ13C) for identification of marine food consumption. Previous studies have compared lg(Ba/Sr) values between different species of animals with differing diets, but few studies have been performed where animals of the same species consumed known diets ranging from completely terrestrial to completely marine. Additionally, how seaweed consumption affects dental and bone Ba, Sr and other trace element concentrations has not yet been directly investigated. In this study, tooth enamel from modern sheep (n = 15) that consumed known diets containing varying amounts of terrestrial grasses and seaweeds were analysed for their Sr, Ba, Ca, V, Mn, Co, Ni, As, and U concentrations. Additionally, δ13C values were analysed to enable comparison of δ13C and trace element ratios as markers of marine plant food consumption. The consumed vegetation types (grasses and seaweeds) were also analysed for trace element ratios, as were soils and sands from areas where the animals were pastured. To investigate how decay processes (i.e., diagenesis) may affect lg(Ba/Sr) in archaeological tooth enamel, teeth of 22 sheep from seven archaeological sites (ranging from ca. 5000 to 1000 years old) on the Orkney Islands, Scotland, were also analysed. The results show that tooth enamel from seaweed-eating sheep had significantly different lg(Ba/Sr) (−2.4 to −1.6) and δ13C values (−6.7‰ to −3.3‰) when compared to terrestrial-feeding sheep (lg(Ba/Sr) 0.6 to −0.5; δ13C −15.5‰ to −14.7‰), with a linear correlation between lg(Ba/Sr) and δ13C (R2 = 0.94). Vegetation, soil and sand results confirmed the assumed dependence of enamel lg(Ba/Sr) values on the (bioaccessible) Ba and Sr concentrations of the consumed matter. The archaeological samples had elevated relative amounts of U, V, As, Mn, Co, and Ni, attributable to diagenesis. However, the lg(Ba/Sr) values of the archaeological enamel followed the trend established using the modern samples, indicating that diagenesis did not cause significant changes in lg(Ba/Sr) in these samples. In conclusion, lg(Ba/Sr) values in enamel appear to be a useful indicator of the relative amount of marine food consumed, including seaweeds. This may be particularly advantageous for samples and locations where δ13C is unreliable or ambiguous as an indicator of marine food consumption.
KW - Arsenic (As)
KW - Biomagnification
KW - Calcium biopurification
KW - log(Ba/Ca)
KW - log(Ba/Sr)
KW - log(Sr/Ca)
KW - Palaeodietary modelling
KW - Stable carbon isotopes (δC)
KW - Trace elements
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U2 - 10.1016/j.jas.2022.105551
DO - 10.1016/j.jas.2022.105551
M3 - Article
AN - SCOPUS:85123751705
SN - 0305-4403
VL - 139
JO - Journal of Archaeological Science
JF - Journal of Archaeological Science
M1 - 105551
ER -