The 2002/2003 radionuclide concentration in the marine environment at various distances from the Barsebäck nuclear power plant

Abstract

The activity concentration of (CS)-C-137, I-131, Zn-65, Co-60, Co-58, Mn-54, and K-40 were determined in samples of brown seaweed (Fucus) and some other marine plants using low background high-resolution gamma-spectrometry. The algae were mainly sampled in the bay just north of the Barseback NPP (55.4 N, 12.6 E) in the south of Sweden to study the contamination levels in the nearest shallow waters. One aim of the study was to investigate whether the levels were high enough to expect environmental effects. Some samples were also taken at longer distances up to 130 kin from the Barseback NPP. Measurable levels of the neutron activation products Zn-65 (up to 17 Bq/kg dw), Co-60 (100-600 Bq/kg dw), Co-58 (1-160 Bq/kg dw) and Mn-54 (12-90 Bq/kg dw) were found in the algae samples within a distance of 5 kin from the plant. The decrease in activity concentration with distance from the plant could he described by a power function with an exponent ranging from 1.4 to 2.4. This was in fair agreement with the value for a true two-dimensional dispersion model. The present-day concentrations were found to be considerably lower than in earlier studies made in the late 1970s, especially for Zn-65 and Co-58. The activity concentration of gamma emitting radionuclides in Fucus vesiculosus from the bay just north of Barseback in the period 2002-2003 was dominated by (in order of decreasing concentration): natural K-40, Co-60 from the plant, Cs-137 mainly from the Chernobyl debris, Mn-54 and Co-58 from the plant. It is not likely that any effects from the very marginal absorbed dose contribution from the Barseback NPP releases can he found even in the nearest environment. The study has also shown that the eelgrass Zostera marina may be a bioindicator to use in further studies of the radiation environment in shallow water, especially for Co-60 and Mn-54. (Less)