Freshwater radiocarbon reservoir effects at the burial ground of Minino, northwest Russia

If ancient carbon is incorporated into lakes and rivers, it can be transferred along the foodchain where it can cause radiocarbon dates to appear erroneously old. This effect is known as the ¹⁴C freshwater reservoir effect (FRE), and causes particular problems when dating human remains. Several studies have attempted to use carbon and/or nitrogen stable isotopes to predict the size of the FRE, with mixed success. We have examined whether the FRE at the Mesolithic-Neolithic burial ground of Minino, northwest Russia, is correlated with these stable isotope systems. To assess the size of the FRE, 9 pairs of human bone and burial goods were dated, such as spears and pendants made of herbivore bone. In addition, further human and faunal bones were analyzed for carbon and nitrogen stable isotopes. Although these stable isotopes suggest that freshwater resources dominated the protein intake of those buried at Minino, no relationship between stable isotopes and the FRE was found. Instead, we found that the FRE was relatively consistent at 490 ± 80 ¹⁴C yr. With caution, this can be subtracted from burials at Minino to provide a low-resolution chronology for the burial ground. We demonstrate that it is not possible to assume that a relationship exists between stable isotopes and ¹⁴C, and each population thought to be affected by a FRE must be examined individually.