Assessing the Radiocarbon Freshwater Reservoir Effect for a Northwest-European River System (the Schelde Basin, Belgium)

The freshwater reservoir effect (FRE) for the Schelde basin (Belgium) is assessed for the Roman, Medieval and early Post-medieval periods by comparing historical and archaeological dates from individual archaeological deposits with radiocarbon dates on the remains of freshwater fish and terrestrial mammals from those same deposits. This is the first time such an assessment has been attempted for the Schelde basin. The FRE offsets prove to be substantial for the historical periods considered. They also differ markedly between fish species and between size classes of a single species. These observations have implications for the evaluation of radiocarbon dates obtained on archaeological remains of humans (and animals) with a substantial amount of freshwater fish into their diet. The data obtained in this study suggest that it will not be easy to correct for any FRE.