engleski

Spatial distribution of uranium and radium in the sediments, mussels (Mytilus sp.) and sea water in port of Šibenik

The purpose of this study is to assess the response of the aquatic environment (sediment, seawater and mussels Mytilus sp.) on uranium and radium activity and concentration following the decrease of phosphate discharges from a technologically improved transhipment terminal, situated at Croatian Adriatic coast in port of Šibenik. The highest 238U activities (485+-16 Bq kg-1 dry weight) and 226Ra activities (662+-6 Bq kg-1 dry weight) were found in the sediment sample collected from sampling site closest to the terminal. The maximum concentrations in the sediment samples are above the natural ranges and are clearly indicative of technological influence. Mussel samples from port of Šibenik showed levels of 238U activities in the range from 12.1+-2.9 to 19.4+-7.2 Bq kg-1 dry weight and 226Ra activities from 1.9+-0.5 to 5.9+-1.1 Bq kg-1 dry weight, what is few times higher than in consume mussels. Only the seawater sample at sampling site, taken just above the bottom sediment, shows higher uranium concentration (3.1+-0.2 &micro ; ; g L-1) comparing to the samples taken in upper seawater layers (2.1+-0.2 &micro ; ; g L-1). Higher concentration is in the range of the concentration level of uranium in natural seawater. Since the transhipment terminal in port of Šibenik was modernised in eighties, discharge of the phosphate ore into the seawater drastically reduced and, consequently, uranium concentration levels in seawater have decreased. The enhanced uranium and radium activity levels are found only in the sediment near operational docks, and in the mussels which live on this docks.

uranium; radium; sediment; seawater; mussels Mytilus sp.; Krka river Estuary; phosphate

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