Pre- and post-Chernobyl accident levels of 129I and 137Cs in the Southern Baltic Sea by brown seaweed Fucus vesiculosus.

129I is a very long-lived radionuclide (T1/2 = 15.7 × 106 years) that is present in the environment both because of natural and anthropogenic sources. In this work 129I concentration and 129I/127I ratio have been determined in seaweed Fucus vesiculosus collected in the Southern Baltic Sea during 1982 and 1986 (post-Chernobyl accident). The resulting data were evaluated in terms of 129I concentrations, 129I/127I and 129I/137Cs ratios. 129I concentrations were found to be in the order of (0.82–5.89) × 109 atoms g−1 in 1982 and (1.33–38.83) × 109 atoms g−1 in 1986. The 129I/127I ratios ranged from (22.7–87.8) × 10−10 for seaweed collected in 1982 and from (26.1–305.5) × 10-10 for seaweed collected in 1986. Also a linear relationship was established for 127I concentrations in seawater and salinity in this area, enabling the estimation of concentration factors for 127I in F. vesiculosus.