Variation in the radiocarbon age of different fractions of peat: A case study from Ahrenshöft, northern Germany

► We 14C date humin and humic acids from different grain-sized fractions of peat. ► The peat was sampled from the open-air archaeological site at Ahrenshöft, Germany. ► Humin ages increased with increasing grain size due to rootlet contamination. ► Unexpectedly, humic acid ages also increased with increasing grain size. ► We find humic acid ages are generally younger than corresponding humin ones.