engleski

INFLUENCE OF PHOSPHATE ORE TRANSHIPMENT ON 238U AND 226Ra DISTRIBUTION IN KRKA RIVER ESTUARY, CROATIA

Phosphate ores are enriched in uranium series radionuclides, especially 238U and 226Ra. The phosphate industry and transport of phosphate ore is considered as one of the potential sources of natural radionuclide contamination (238U and 232Th decay series). Šibenik is the main Croatian port for phosphate ore import, situated on the Krka River estuary nearby Krka National Park. The aim of this study was to assess the impact of phosphate ore transhipment on the Krka River estuary following 238U and 226Ra distribution in sediments and biota. Activities of 238U and 226Ra were determined by gamma spectrometry using a low-background germanium (HPGe) “Canberra” semiconductor detector system. In the port near transhipment facility it was found significant enhancement of uranium and radium activities in deeper sediment layer (662±6 and 485±16 Bq kg-1 dry weight for 226Ra and 238U, respectively), while in the recent sediments activities were markedly lower. Modernization of facilities in 1988 was unequivocally successful. Radionuclide activities in mussels’ tissue (Mytilus sp.) collected in close vicinity of the port, were markedly enhanced. Activities of 238U in mussels (Mytilus sp.) were in the range from 12.1±2.9 to 19.4±7.1 Bq kg- 1 dry weight. These activities were few times higher than in mussels (2-3 Bq kg-1 dry weight) originating from other parts of Krka River estuary. Examination of spatial distribution of uranium and radium in sediments showed that impact from phosphate ore transshipment facility stayed restricted in port and did not spread into Krka River estuary.

phosphate ore; radionuclides; uranium; radium

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