BOND C-13/C-12 RATIOS REFLECT (PALAEO-)CLIMATIC VARIATIONS

Stable isotope ratios of hydrogen, oxygen, nitrogen and carbon can serve as (palaeo-) environmental indicators [eg, Ramesh et al., 1986] . H-2 and O-18 have the clearest relationship with precipitation and temperature, while the sensitivity of carbon is thought to be far less pronounced, and understanding is not complete. Carbon isotopic variation in ecosystems is mainly due to photosynthesis in plants, and passed on in the foodweb without much overall modification (this enables palacodiet reconstructions using archaeological bone [Schwarcz, 1991]). Using radiocarbon databases [Van der Plicht, 1992] which also contain C-13 data, we have compared a number of European countries for geographical variation in C-13/C-12 ratio of archaeological wood, charcoal and bone samples. We find similar trends for all three materials. A significant trend from northwestern to southern Europe exists in the plant samples, which we relate to climatic differences influencing C-13/C-12 ratios during carbon fixation. This shift passes through the food web, and is thus found in the bone samples, which makes it possible to use accumulated bone stable isotopic data for palacoclimatic reconstructions.