An Icelandic freshwater radiocarbon reservoir effect: implications for lacustrine 14C chronologies

Ascough, P. , Cook, G. , Hastie, H. , Dunbar, E. , Church, M.J., Einarsson, A., McGovern, T.H. and Dugmore, A.J. (2011) An Icelandic freshwater radiocarbon reservoir effect: implications for lacustrine 14C chronologies. Holocene, 21(7), pp. 1073-1080. (doi: 10.1177/0959683611400466)

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A freshwater radiocarbon (<sup>14</sup>C) reservoir effect (FRE) is a <sup>14</sup>C age offset between the atmospheric and freshwater carbon reservoirs. FREs can be on the order of 10 000 <sup>14</sup>C yr in extreme examples and are a crucial consideration for <sup>14</sup>C dating of palaeoenvironmental and archaeological samples. Correction for a FRE may be possible, provided the FRE and the proportion of FRE-affected carbon within a sample can be accurately quantified. However, although such correction is desirable for affected samples, it is essential that such correction is accurate in order to produce useful chronological information. Accuracy of FRE correction can be limited by spatial variation in FRE within a freshwater system, but despite this there is currently a paucity of information to identify and quantify such variability within affected systems. Here we present results of a study that investigates the effects of spatial FRE variation upon dating accuracy within the freshwater system of Lake Mývatn, northern Iceland. A substantial FRE (>10 000 <sup>14</sup>C yr) has previously been identified in archaeological and modern samples from the region, which shows the potential for considerable spatial variability. The study also assesses the use of δ<sup>13</sup>C and δ<sup>15</sup>N in age correction of affected samples. The results show that benthic detritus and organisms at primary trophic levels from locations within the lake are affected by a FRE of at least 3500 <sup>14</sup>C yr, with clear spatial variation resulting in <sup>14</sup>C age differences of up to 7670 <sup>14</sup>C yr between samples. There is a broad correlation between stable isotope values and FRE within the data set. However, large associated uncertainties currently preclude highly accurate and precise stable isotope-based quantification of the proportion of FRE-affected carbon within archaeological and palaeoenvironmental samples from Mývatn and the surrounding region.

Item Type:Articles
Glasgow Author(s) Enlighten ID:Dunbar, Dr Elaine and Cook, Professor Gordon and Kinch, Ms Helen and Ascough, Dr Philippa
Authors: Ascough, P., Cook, G., Hastie, H., Dunbar, E., Church, M.J., Einarsson, A., McGovern, T.H., and Dugmore, A.J.
Subjects:G Geography. Anthropology. Recreation > GE Environmental Sciences
College/School:College of Science and Engineering > Scottish Universities Environmental Research Centre
Journal Name:Holocene
Publisher:Sage Publications Ltd.
ISSN (Online):1477-0911
Published Online:11 March 2011
Copyright Holders:Copyright © 2011 Sage Publications Ltd.
First Published:First published in The Holocene 21(7):1073-1080
Publisher Policy:Reproduced in accordance with the copyright policy of the publisher

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