Distribution and transfer of naturally occurring radionuclides and 137Cs in the freshwater system of the Plitvice Lakes, Croatia, and related dose assessment to wildlife by ERICA Tool

• Published in: Environmental science and pollution research international 2021-05, Vol.28 (18), p.23547-23564
• Main Authors: Skoko, Božena, Babić, Dinko, Franić, Zdenko, Bituh, Tomislav, Petrinec, Branko
• Format: Article
• Language: English
• Subjects: Aquatic Pollution; Atmospheric Protection/Air Quality Control/Air Pollution; Cesium 137; Cesium isotopes; Cesium radioisotopes; Dosage; Earth and Environmental Science; Ecotoxicology; Environment; Environmental Chemistry; Environmental Health; Environmental science; Fish; Freshwater fish; Geology; Lakes; Lead isotopes; Mathematical analysis; National parks; Natural radioactivity; Nuclear accidents; Radioactivity; Radioisotopes; Radium; Radium 226; Radium isotopes; Radium radioisotopes; Research Article; Risk assessment; Sediments; Spectrometry; Waste Water Technology; Water activity; Water analysis; Water distribution; Water engineering; Water Management; Water Pollution Control; Water sampling; Wildlife
• ISSN: 0944-1344; 1614-7499
• DOI: 10.1007/s11356-021-12415-w

The aim of this study was to investigate the natural radioactivity of Plitvice Lakes, under the assumption that due to its status as a National Park, the area can be considered an example of a natural freshwater system. Also, considering the transfer parameter data as the largest source of uncertainty in radiological risk assessments, the impact of site-specific data on dose rate assessment, as opposed to currently available data, was investigated. The study included gamma and alpha spectrometric measurements of 238 U, 226 Ra, 210 Pb, 228 Ra, and 40 K in water, sediment, and fish samples, as well as 137 Cs due to the coinciding of the study with the Fukushima accident. The content of naturally occurring radionuclides significantly varied in sediments of different Lakes, probably as a reflection of the different underlying geology of the area. Also, the 210 Pb distribution in sediments indicated an up to 312 Bq kg −1 of the allochthonous contribution of this radionuclide at the beginning of the Lake’s watercourse, which probably entered into the lake system by the major inlet river with its steady decrease along downstream lakes. Low 40 K activity concentrations (27.5 ± 20.1 mBq L −1 ) in the Lake’s waters might be one of the causes of increased 137 Cs activity concentrations in fish samples (1.5 ± 0.4 Bq kg −1 ), which was found to be an order of magnitude higher than average values for different fish species from other Croatian freshwater systems (0.2 ± 0.1 Bq kg −1 ). A temporary increase of 137 Cs activity concentrations was measured in water samples collected immediately after the Fukushima accident. Calculated site-specific sediment/water distribution coefficients and fish/water concentration ratios for radium and caesium were on average lower than generic ones found in the literature. Background dose rate assessments performed by the ERICA Tool indicated a profound impact of different input data on assessment results with water activity concentrations resulting in significantly higher dose rates (0.1–67 μGy h −1 ) in comparison to sediment activity concentrations (0.03–9 μGy h −1 ). An incremental dose rate due to 137 Cs was found to be in the range of < 0.001–0.023 μGy h −1 which, in comparison to background dose rates, can be considered negligible.