Interspecies comparison of marine reservoir ages at the Kitakogane shell midden, Hokkaido, Japan Minoru Yoneda a, * , Yasuyuki Shibata a , Masatoshi Morita a , Masashi Hirota b , Ryo Suzuki b , Kazuhiro Uzawa c , Naoyuki Ohshima d , Yukio Dodo e a National Institute for Environmental Studies, Onogawa 16-2, Tsukuba, Ibaraki 305-0053, Japan b Environmental Research Center, Ltd., Hanare 3-1, Tsukuba, Ibaraki 305-0857, Japan c University of East Asia, Ichinomiya Gakuen-cho 2-1, Shimonoseki, Yamaguchi 751-8503, Japan d Date City Board of Education, Matsugae-cho 34-1, Date, Hokkaido 052-0012, Japan e Graduate School of Medicine, Tohoku University, Seiryo-machi, Aoba, Sendai, Miyagi 980-8575, Japan Abstract Apparent 14 C ages of human and faunal remains from the Kitakogane shell midden assigned to the Early Jomon period were measured to estimate the reservoir effect on different species. In previous studies, northern fur seal and Japanese deer had showed significant age differences of 860 14 C yr, in concordance with the large reservoir ages ob- served in pre-bomb shells from the western North Pacific. However, the present study suggests that other sedentary marine organisms, including porpoise, Japanese sea lion and scallop, show a smaller reservoir age-offset at 720 14 C yr at the same site. The ethology of northern fur seal was probably responsible for this discrepancy because of a larger reservoir age in the Sea of Okhotsk into which they migrated. This suggests the reservoir effect on humans was more complicated than a simple linear mixing between marine and terrestrial reservoirs in the case of the NW Pacific coast. It was suggested that an interspecies comparison of 14 C age-offsets could produce more precise estimation of the marine reservoir effect in the past. Ó 2004 Elsevier B.V. All rights reserved. PACS: 91.65.Br; 91.65.Dt Keywords: Marine mammal; Diet; Shell; Human bone; Jomon period; Marine reservoir effect 1. Introduction The radiocarbon ( 14 C) dating is the most important dating method for the age determina- tion of the Late Quaternary samples. However, the precise age determination of marine samples has not fully established and this is a big problem for palaeo-environmental studies because, for exam- ple, marine cores are one of the important sample for palaeoceanography. The difficulty is mainly caused by the variability and complexity of marine reservoir ages in space and time. 14 C ages of marine samples are generally several hundreds older than the contemporaneous atmospheric res- ervoir because of the larger size of marine reservoir * Corresponding author. Tel.: +81-298-50-2552; fax: +81- 298-50-2574. E-mail address: myoneda@nies.go.jp (M. Yoneda). 0168-583X/$ - see front matter Ó 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.nimb.2004.04.073 Nuclear Instruments and Methods in Physics Research B 223–224 (2004) 376–381 www.elsevier.com/locate/nimb