[en] The objective of this Seminar was to bring together specialists in marine radioecology, to discuss selected topics and thereby to contribute to a better understanding of the consequences of radioactive waste sea during operations and of isotope releases from reprocessing and reactor operations

[en] Except in 1972, during the years 1966 to 1974 at all stations a decrease of the activity concentration values of the radioisotopes Cs 137 and Sc 90 from surface down to deeper layers could be observed. However, at several stations taken along a line between the Biscay and the Azores, as well as in the northern North Atlantic at 60⁰, 70⁰ and 72⁰ N during the year 1972 we could observe in a depth region of about 750 to 1250 m an increase of the activity concentration values of Cs 137 up to two to eight times of the corresponding values in the surface water. The vertical distribution of Sr 90 does not indicate the same anomaly. Therefore it seems to us, that this concentration effect may be explained by biological processes

[en] ECN at Petten carries out a survey on the occurrence of trace metals in coastal marine organisms. The survey is aimed to provide an estimate of concentration factors in local marine organisms for neutron activation products released as low-level liquid radioactive waste into the North Sea. The organisms studied are red and brown seaweed, edible mussels ans shrimp. A summary of the results of analyses of iron, cobalt, zinc, silver and antimony in these organisms is presented. Concentration factors derived from mean stable-element concentrations range from about 50 for Sb in red seaweed and shrimp to about 10⁴ for Fe in red seaweed and mussels. The largest variation is shown for zinc in seaweed, which variation is seasonal and most pronounced in brown seaweed. A discussion of the data is presented in relation to data from other West-European coastal areas and to data used for the radiological assessment of deep sea disposal of radioactive waste

[en] Data on regional sedimentary processes, in conjunction with measurements of Pb-210 activity distributions in short cores, facilitate the differentiation of local bioturbation regimes on the continental slope, east of Newfoundland, and provide insight into the factors controlling sediment mixing in these and comparable environments. Excess Pb-210 is confined to the upper 2 cm of sediments underlying the southerly-flowing, Western Boundary Undercurrent (WBU) at 2600 m indicating that minimal contemporary biological reworking of material has occurred at this location. This regime represents an inhospitable environment for the establishment of bioturbating communities because: (1) deposition of fine-grained, organic-rich material which serves as a food source for benthic infauna is inhibited by bottom currents which attain speeds of at least 20 cm s^-1, and (2) the variable current regime produces an unstable bottom substrate in which smaller organisms (e.g. meiofauna) are frequently buried and their burrows are rapidly infilled. In contrast, the higher flux of fine-grained, organic-rich material to the middle slope (700 to 2000 m), and the more stable sedimentary conditions which prevail in this low energy regime, are conducive to active colonization of this substrate by bioturbating macrofauna. Maxima in Pb-210 activity profiles at depths of 7 cm to 11 cm in sediment cores are suggestive of heterogeneous, down-ward transport of surface material, possibly through infilling of macrofaunal burrows

[en] Fucus serratus and F. vesiculosus collected at the Swedish south west coast during 1967-1978 have been analyzed. Uranium was found in highest activity concentrations; 13, 11 and 0.45 Bq/kg dry weight of U-234, U-238 and U-235 respectively, which correspond to dry weight concentration factors of about 700 for uranium isotopes. The activity concentrations of thorium isotopes were 100, 400, and 7000 mBq/kg dry weight of Th-232, Th-230 and Th-228 respectively. Concentrations of Pu-239+240 in this bioindicator ranged from 100-600 mBq/kg dry weight and of Am-241 from 10-50 mBq/kg dry weight, depending on which year and site of collection. In unfiltered seawater we find in 1978 Pu-239+240 and Am-241 of concentrations in the order of 7-14 μBq/l and 2-3 μBq/l respectively. The dry weight concentration factors were about 12000 for Pu and 20000 for Am

[en] In order to know factors which influence Co-60 contamination of sargassoes in Urazoko Bay, where a nuclear power plant is located, correlations between the contaminations of the algae and of the marine environment were investigated, based on field data observed since January 1971. It was found that correlation between the Co-60 content in sargassoes (Y(algae) pCi/kg raw weight) and distance from discharge outlet of the nuclear power plant to the sampling points (d km) was expressed by a function, Y(algae) = C.exp(-kd). Where C and k are constants, and k fluctuated from 0.388 in November 1971 to 1.200 in November 1974, whereas C decreased from 120 to 27 during the same period. Based on the results of the investigation and the laboratory tracer experiments, the destiny of the radionuclides released into coastal sea was discussed

[en] The amounts of several stable elements in mesopelagic organisms were measured to determine the concentration factors of these elements on the assumption that the contamination by the radioactive materials due to deep sea disposal of radioactive wastes. The concentration factor is one of the important parameters used to evaluate the internal radiation doses to man by the intake of the contaminated organisms. The levels of Cs-137 and Sr-90 due to fallout in the mesopelagic fishes were also investigated with interest in vertical transfer of the nuclides in the sea

[en] Research programme and experience, in connection with coastal discharge of radioactive liquid wastes, during past fifteen years, were summarized. In the first stage, i.e. period obtained only limited practical scientific information, pre-estimation of radiation doses to man with theoretical and assumed factors, weighted enough safety, was carried out. During the second stage, further practical estimation was obtained by use of experimental results and survey data. At the third stage, environmental monitoring data are going to prepare for scientific analysis and safety control of the radioactive effluent. At the same time, radioecological studies on the aquatic organisms in coastal waters and also technical studies on the waste treatment are investigated continuously

[en] Adaption characteristics of the benthic communities to life at the abyssal sea floor, vertical migrations of different organisms and food chains are referred. Consequences of drums dumping are also considered. It comes out that radioactive materials may reach the surface by upwelling, throughout the usual food chains or through a new exploitation of the fishing resources at greater depths

[en] A summary is given of studies on the behaviour of radionuclides in the Baltic Sea. The balances of ⁹⁰Sr and ¹³⁷Cs in water phase are discussed as well as their elimination from water by sedimentation and distribution in sediments. The distribution of ²³⁹Pu, ²⁴⁰Pu in sediments is also described. In soft bottoms the amount of ⁹⁰Sr per unit area varies from 6 to 15% of that deposited on land surface, ¹³⁷Cs from 17 to 700% and ²³⁹Pu,²⁴⁰Pu from 65 to 1000%. Accumulation of the above-mentioned radionucides as well as ⁵⁴Mn, ⁵⁸Co, ⁶⁰Co, sup(110m)Ag and ¹²⁴Sb by some Baltic mussels, a crustacean different littoral algae, plankton and some fish species is reported