Carbon and Pu isotopes in Baltic Sea sediments

Distributions of 137Cs, 239,240Pu, Δ14C and δ13C measured in sediments indicated low 137Cs and 239,240Pu activities in the Curonian Lagoon and higher levels in the open Baltic Sea. Depleted δ13CTOC values were found in the Curonian Lagoon as compared with the open Baltic Sea, while the most depleted Δ14CTOC values were found in the Gotland Deep. The global fallout Pu dominated in the deeper zones of the Baltic Sea, while higher 240Pu/239Pu atom ratios were characteristic of the coastal regions. •137Cs and 239,240Pu activities varied from 1 to 200Bq/kg and from 0.03 to 3Bq/kg, respectively.•The most depleted Δ14CTOC values were found in the Gotland Deep.•The 240Pu/239Pu ratio frequency distribution showed the most typical value of 0.185.•The lowest the Chernobyl-derived Pu contribution was found in the Gotland Deep.