Stable isotope compositions and trace element concentrations in freshwater bivalve shells (Unio sp.) as indicators of environmental changes at Tiszapuspoki, eastern Hungary

摘要

Stable carbon and oxygen isotope compositions of living Unio shells and oxygen isotope compositions of water samples were determined in order to demonstrate how the shells' compositions can reflect environmental conditions. With this information in hand, fossil shell fragments from a sedimentary section at Tiszapuspoki covering the period of about 3.5 to 10 ky BP were analyzed for their stable isotope as well as trace element compositions. Beside the determination of sedimentary facies effects on the geochemical compositions, the combined evaluation of isotopic and trace element records allowed us to detect past environmental changes at a millennial scale. The data indicate that the period of 6 to 8 ky BP was characterized by humid summers that - on the basis of comparison with an Alpine speleothem record - was associated with a generally warmer climate and increased winter precipitation in the Alps.