engleski

Origin and transport of 238U and 226Ra in riverine, estuarine and marine sediments of the Krka River, Croatia

Spatial distribution of 238U and 226Ra activities in sediment columns along the Krka River and estuary, were studied using gamma spectrometry. Markedly different 238U and 226Ra activities between riverine, estuarine and marine sediments were observed. Distribution of these radionuclides, as well as their anthropogenic and natural origin, was evaluated by activity measurements, taking into account sedimentation rates estimated by 137Cs distribution in sediment columns. Naturally present 238U and 226Ra activities were highest in riverine and lowest in marine sediments. 238U and 226Ra activities in historic riverine sediments revealed anthropogenic influence from town of Knin, which diminished for 15 - 20 % in 1990s due to warfare that caused stop of industrial, agricultural and transport activities. Drainage of the flysch material naturally elevates 238U and 226Ra activities in the vicinity of its inflow in the upper part of estuary. 238U and 226Ra from the phosphate ore discharge in the port of Šibenik did not spread further in estuary, which was also confirmed by 238U and 226Ra activities detected in Mytilus sp. mussels’ tissue.

238U ; 226Ra ; 137Cs ; radionuclide ; sediment ; mussels Mytilus sp. ; Krka River estuary ; gamma-spectrometry

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