Koster HW ,
Marwitz PA ,
Berger GW ,
Weers AW van ,
Hagel P ,
Niewenhuize J
232 p
in Dutch
1990
Toon Nederlands
English Abstract In 1985/1986 reconnaissance investigations were carried
out of Po-210, Pb-210, Ra-226, Th-230 of the U-238 decay series, and of
Th-232 and its daughter Th-228. In the lower reaches of the Rhine, the
Westerschelde and the Hoogoven(furnace)-channel concentrations were markedly
elevated. The average Po-210 concentrations of these waters were between 3
and 4 Bq.m-3 dissolved in water, between 200 and 500 Bq.kg-1 in dry
suspended matter, between 300 and 400 Bq.kg-1 in mussels dry matter. These
elevated levels could be ascribed to emissions on these waters by the
phospate rock and the iron ore-processing industries. In bottom sediment of
waterways or of docks close to these industries Pb-210 and Po-210
concentrations varied from 150 to 750 Bq.kg-1 dry sediment. The lowest
average Po-210 concentrations were found in the Oosterschelde: 0,8 Bq.m-3
dissolved in water, 70 Bq.kg-1 in dry suspended matter, 100 Bq.kg-1 in
mussels dry matter. It was found that several organisms incorporate Po-210
more strongly than the other natural radionuclides. Po-210 also contributes
most to the radiation burden caused by the consumption of fish products, in
particular of mussels and shrimps. Consumption of 1 kg.a-1 of shrimps from
the Oosterschelde or from the coastal area causes respectively a radiation
exposure of 10 muSv.a-1 or 30 muSv.-1. The study points out the necessity
for further studies of the emissions of Po-210 and other U-238 daughters and
their dispersal and/or accumulation in the aquatic environment. Furthermore
it is important to identify critical groups with respect tot the radiation
exposure cuased by the consumption of mussels and other fish products, and
the contribution to this radiation exposure by the
industries.
