Uranium and thorium in muscle tissue of fish taken from the southern Baltic

The determination of U and Th was carried out on pooled samples of muscle tissue of cod (Gadus morhua), herring (Clupea harengus), sprat (Sprattus sprattus) and some other species of fish caught in 1981 in the southern Baltic. The levels of U obtained in the present study are generally within the ranges presented by other authors for fish from different aquatic regions of the world. The concentrations of U are similar to those found for Th in Baltic fish analysed. The concentration factors CF_U(Th), discrimination factors DF_U/Th and Th/U ratios (by weight) were calculated and discussed. These coefficients were also compared with values determined in other Baltic organisms. Transfer of U and Th along a food chain from potential prey (diet) to fish as predator (consumer) was quantified with a transfer factor.