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

Biodistribution of naturally occurring radionuclides and radiocesium in wild European perch (Perca fluviatilis)

Wild European perch (Perca fluviatilis) is one of the most important freshwater fish species, in Sweden, due to its widespread and his value for recreational fishing. Little it is known regarding the biodistribution of naturally occurring radionuclides such as ²³⁸U, ²³⁴U, ²²⁶Ra, ²¹⁰Po in perch. Therefore, in this study, perches from five lakes located in different counties in Sweden were collected to investigate the biodistribution of ²³⁸U, ²³⁴U, ²²⁶Ra, ²¹⁰Po and ¹³⁷Cs in organs and tissues of perch as well as their radiological impact. The results showed that uranium radionuclides ranged between 0.1 and 6 Bq/kg with an average value of 1.1 ± 1.5 Bq/kg. ²²⁶Ra varied from 0.4 to 8 Bq/kg with a mean concentration of 1.7 ± 1.9 Bq/kg. The ranged of ²¹⁰Po was 0.5 - 250 Bq/kg, with an average value of 24 ± 52 Bq/kg. On the other hand, the highest activity concentration of ¹³⁷Cs, 151 ± 1 Bq/kg, was detected in muscle samples of perch from Redsjösjön lake. For uranium radionuclides and ²²⁶Ra uptake from water is the main source whereas for ²¹⁰Po and ¹³⁷Cs the uptake is controlled by the perch diet. Regarding naturally occurring radionuclides, the perch tended to accumulated uranium radionuclides in fins, gills, and skin; ²²⁶Ra in bones, fins and skin and ²¹⁰Po in the organs linked to digestive system. Finally, in case of consumption, it is advised the consumption of skinned fillets of perch due to the higher bioaccumulation of the radionuclides investigated in the skin and scales.

Sedimentary conditions based on the vertical distribution of radionuclides in small dystrophic lakes: a case study of Toporowe Stawy Lakes (Tatra Mountains, Poland)

The aim of this work was to prove the use of radionuclides deposited in sediment core taken from an overgrowing dystrophic lakes surrounded by marsh-peat vegetation to estimate sedimentary conditions. Sediment core samples were taken from the Toporowe Stawy Lakes (Niżni (TSN) and Wyżni (TSW); Tatra Mountains). The sampling was done using a Limnos corer. After the physical sample preparations, gamma measurements were performed. Radiochemical analysis was applied with the aim of determining 210Pb radioactivity by means of 210Po. The mean values for TSN lake are as follows: 137Cs ~ 123 Bq∙kg-1, 40 K ~ 389 Bq∙kg-1, 228Th ~ 55 Bq∙kg-1, 226Ra ~ 86 Bq∙kg-1, 241Am ~ 5 Bq∙kg-1, and 210Pbuns ~ 180 Bq∙kg-1. For TSW lake, the radioactivity levels of 226Ra and 241Am are comparable to the TSN. The mean values of 137Cs, 40 K, and 228Th are almost twice as high as in TSN. The level of 210Pb in uppermost layer of TSN is higher than in TSW. Sediments were dated by use of 210Pb method, and the rate of sedimentation of each layer was also estimated. Basic chemometric tools were used to confirm the way of deposition of radionuclide, find the correlations between variables, and compare analyzed lakes. It was concluded that the presented type of lakes are a valuable source of information and the vertical distribution of radionuclide can be used to interpret the source of material supply and factors that influence the sedimentation process in recent 150-200 years.