REPORT NO. IAPA-n-421-P *ÏVe TITLE Radioactive contamination in marine environment and biota in the tasin of the Mediterranean Sea (part of a coordinated programme of research in marine radioactivity studies) FINAL REPORT FOR THE PERIOD 1 December 1966 - 2(J February 1971 AUTHOR(S) E. Gilat N.H.Steiper-Shafrir Í INSTITUTE Technion - Israel Institute of Technology Department of Nuclear Science Haifa, Israel INTERNATIONAL ATOMIC ENERGY AGENCY Í DATE December 1971 V;: rv-.sr-y-;-: í • i,-¿..£.: "Ijj TNSD4/42S -^ Israel" Institute of Technology Department of Nuclear Science RADIOACTIVE CONTAMINATION IN MARINE ENVIRONMENT < AND BIOTA IN THE EASTERN BASIN OF THE MEDITERRANEAN SEA FINAL REPORT i • '•. ;-, - j ;'• • - .^ ;'•J ' ' T' • ;¿;,_>-.^.?u: N. H. Steiger-Shafrlr ^*/! - * l V = - ; v • '' ; / - .j - ' \ '•: - '"•?" ' „•o -í.; • ° S \ -t" -, - Í * 4; :' £ .', • TNSD-R/423 Sea Fisheries Research Station, Department of Nuclear Science, Ministry of Agriculture* TECHNION-Israel Institute of Technology* RADIOACTIVE CONTAMINATION IN MARINE ENVIRONMENT AND BIOTA IN THE EASTERN BASIN OF THE MEDITERRANEAN SEA FINAL REPORT E. Gilat* and N.H. Steiger-Shafrir** The research was partially supported by the International Atomic Energy Agency, Vienna, under Research Contract No. 421/RB. Haifa, Israel, November 1971 ' "« \ Acknowledgements The authors wish to acknowledge the participation of the following staff meihbers in the studies carried out under Research Contract No. 421/RB. Mrs. Manuela Wulf Radiochemical Separations Mrs. Jeanette Kamil Radiochemical Separations Mrs. Pauline Chin Radiochemical Separations Mrs. Rachel Tillinger Accumulation Experiments Mrs. Rachel Fischler Ecological Studies Mr. Steven R. Lewis Gamma Spectrometry Mr. Gideon Sachnin Ecological Studies Contents 1. Introduction 2. Ecological Study 2.1 Environmental Conditions 2.1.1 Granulometric Analysis of Sediments 2.2 Distribution of Marine Organisms 3. Method and Experimental 3.1 Sampling of Sea Water and Biota 3.1.1 Sea Water 3.1.2 Biological Samples 90 3.2 Determination of Sr in Sea Water and Biota 3.2.1 Radiocheraical Separation Procedures 3.2.2 Low Level Beta Counting 3.2.3 Measurement Analysis 3.3 Low Level Ge(Li) Gamma Spectrometry 3.3.1 Application of Solid State Detectors to Low Level Gamma Detection 3.3.2 Spectrometer Design 3.3.3 Spectrometer Characteristics 3.3.4 Performance 3.4 Uptake and Loss Experiments 4. Results 4.1 90Sr Content in Sea Water and Biota Samples 4.2 137Cs Content in Sea Water, Biota and Sediment Samples 4.3 Experimental Studies on the Uptake and Loss of Radioelements 4.3.1 Uptake and Loss of Zn in Palaemon elegans 4.3.2 Uptake of 65Zn by Tapes decussatus Discussion List of Benthic Invertebrates Maps w - 1 - 1. Introduction Fission products having sufficiently long half-lives and high fission yields can be detected in marine environment and biota a considerably long time after their release. Therefore among the first radionuclides, strontium-90 and cesium-137 were considered. The first radionuclide to be determined was Sr-90 since it is hazardous being concentrated in bony tissues and has a relatively long biological half-life. Radiochemical separation of sea water and biota samples were performed for Sr-90. The water samples for this purpose were taken in a series of stations in Haifa Bay, as well as in a deep water station situated between the Israeli coast and Cyprus. Samples were taken at various water layers from the surface to a depth of 1000 metres. Preliminary results were obtained for Sr-90 content of the surface waters and later, for the deeper layers. Radiochemical studies were also performed on marine organisms taken in Haifa Bay and in a grid of stations where water samples were also collected. The construction of a heavily shielded large volume Ge(Li) spec- trometry system was completed and put into operation. The system operates in anticoincidence with a large plastic annular detector. Preliminary results of determinations of Cs-137 in sea water and biota are presented. Cesium content was also determined in a number of marine invertebrates and fishes selected for this study, being indicator species of the fauna on the Israeli continental shelf. An ecological survey was carried out in several areas of the continental shelf. The areas which were intensively investigated were as follows: Haifa Bay, Atlit-Netanya and the Ashdod profile. Data on the benthic communities were also collected on the southern section of the continental shelf and off the Sinai Peninsula. A typical profile which provided characteristic data concerning benthic comttunities close to the Suez Canal was the assembly of stations off El-Arish. *•••••'•' - 2 - The fauna was distributed in zones parallel to the coast line and subdivided into areas based on granulometric characteristics of the sediment. Sediment samples were also collected in stations where the ecological survey was carried out and the proportion of sand, silt and clay established and compared with the distribution of benthic inverte- brates. The pattern of distribution of benthic invertebrates fits the characteristics of bottom sediments. These organisms form an important link in the marine food chain being filter and deposit feeders. The filtering process of large volumes of sea water is a source of absorption of radionuclides soluble in sea water. The passage of radionuclides through the marine food chain by ingestion of suspended particles to which radionuclides are adsorbed is one of the important sources of radioactive contamination of marine biota. The determination in quantitative analyses of radionuclides in sea water and marine biota were performed by beta-counting and gamma-spectrometry according to the disintegration characteristics of radionuclides. In the case of Sr-90 radiochemical separation procedures were adopted, while for Cs-137 the same procedure had to be applied using sodium iodide Na(TA) scintillators for gamma-spectrometry. Since these techniques are laborious and time-consuming, the development of high resolution Ge(Li) gamma-ray spectrometers was introduced in the study of Cs-137 content in water samples and marine biota, giving good results in detection of this radio- nuclide. Since the ecosystems in the area investigated are composed of different physiological characteristics - being both of Atlantic and Indo-Pacific origin - it is important to carry out laboratory experiments in the uptake and accumulation of selected trace elements in indicator species which concentrate radionuclides. For this purpose, uptake and loss experiments were carried out on a typical prawn Palaemon which inhabits the coastal area of the Mediterranean. Parallel experiments on the uptake of Zn-65 were carried out on the clam Tapes which inhabits the western Mediterranean. The uptake and loss curves for both organisms, as well as concentration factors in relation to sea water are presented in this study. - 3 - 2. Ecological Study 2.1 Environmental Conditions Temperature and Salinity - The temperature conditions of sea water over the continental shelf were described in detail for the period 1947 - 1965. Data collected within monthly intervals show that the mean temperature.for. the coldest month occurs in March -- 17.14°C at the surface and the maximum is reached in August — 28.64°C, OREN (1964). The temperature conditions for 1967 are presented in fig.(2.1) . Data were obtained from the records-of the bathythermograph and reversing thermometers, made at the time of collection of biological data. (Tables 2.1 and 2.2). The thermocline foundation could be observed at the beginning of May and it was pronounced June to September between the depths of 40-60 metres. The occurrence of a pronounced thermocline on the continental shelf and the changes in its range during spring, summer and autumn may be expected to have a direct effect on the distribution of certain radionuclides in various water layers. It should be remembered that the presence of the discontinuity layer in the sea in relatively shallow waters influences the redistribution of radionuclides which are uptaken by phytoplankton and Zooplankton organisms forming an integral part of the water masses. It may be observed that during July 1967 a thermocline was present along the continental shelf, since measure- ments were made in various localities off Haifa in the north and Rafah in the south, at the sonic depth of 75-130 fathoms. A vertical mixture of the water masses occurs in Decenfcer which may last until April. The formation of a discontinuity layer may be observed in May. The occurrence of a thermocline during the summer is a constant phenomenon in the Israeli waters of the continental shelf and it moves into deeper waters in the autumn. The depth layers in which the thermocline was found, are between 10 and 80 metres. The penetration of density gradients by marine organisms with reference to the distribution of Zn-65 was studied, for the macroplankton in the north Pacific off the Columbia River, PEARCY and OSTERBERG (1967). - 4 - Mediterranean is the temperature of the sea. During the last decade the ris« of temperature and high level of salinity« reduced the physical and cheatcal differences between the northern Red Sea and the eastern Mediterranean. The physical oceano- graphy of the Mediterranean Sea has been discussed by MILLER (196S) who drew conclu» sions from a series of data including the cruise of "Atlantis" (Woods Hole Océano- graphie Institution) in 1961 and 1962 ¿ Miller str.tes that "the source of supply of water in the Mediterranean is primarily the water entering through the Straits of Gibraltar from the Atlantic. Minor influence cones fro« certain rivers and run^off areas such as the area surrounding the Adriatic Sea, the Nile and the inflow through the Straits of Dardanelles". In the eastern Mediterranean the suggestion of POLLÀK (1951) has been confirma, that the deep water there originates in the southern Adriatic Sea. The Bovecent of the cold water masses is in counter-clockwise direction along the bottoa.