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

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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 • '•.

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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.

Table 2.1

Data on Temperatures of the Continental Shelf*

Surface Date Locality Depth in fathoms Temperature (*C)

27.6 .67 Haifa 130 26.5 14.7. 67 Rafah 75 25.9 24.7. 67 Atlit 100 27.0 25.7. 67 tantura 100 27.0 26.7. 67 • Tantura 100 26.6 27.7. 67 Haifa 100 26.9 22.12.67 Tantura 80 19.5 3.4. 68 Haifa 80 17.2 6.5. 68 Tantura 80 17.2

*This Table refers to fig. (2.1). The data were collected during the biological cruises, using a bathythermograph. Table 2.2

Data on Temperatures on the Israeli Continental Shelf* (Centigrades)

LOCA] I I T Y AND D A T E

Depth (netres) Nahariya Nahariya Haifa Nahariya Falmahim Palmahim Palmahim Nahariya Palmahim Netanya 11.8.67 7.11.67 26.12.67 3.3.68 16.6.68 20.10.68 11.11.68 31.1.69 24.3.69 7.4.69

0 28.3 24.4 19.3 16c 4 28.99 25.40 23.93 17.20 17.29 17.50

10 28.3 24.3 19.3 - 27.60 - - - 17.26 17.39 17.35 20 28.2 24.2 19.3 16.3 26.30 25.35 23.90 - 17.20

•*• i - 17.20 17.12 17.20 30 - 24.3 19.3 - 25.63 - i 17.05 50 27.2 23.0 18.9 16.3 27.70 - - - J[ 17.00 17-07 16.88 75 20.5 23.4 - 16.3 18.60 19.05 18.68 - 17.09 16.87 100 17.4 19.0 18.9 16.2 17.60 - - 17.04 - 16.85 125 16.7 17.5 - 16.2 - 16.83 16.93 - - 200 - - 18.5 ------400 • - • - 15.7 - - - -

500 - - 14.7 - - •• __

•Temperatures were taken in Haifa Bay at two stations off Nahariya (depth 75-85 fathoms) and off Haifa harbour in the area where the ecological survey was carried out.

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The Levant Basin of the Mediterranean is a unique area from thé zoogeogra- phical aspect due to the presence of Iñdo-Pacific species.which, since the opening of the Suez Canal, became an important element in the composition of the benthic communities. Since the salinity values in the Suez Canal reached recently a value of 41%o which is the maximum for the northern Red Sea, the penetration of Eritrean species is not limited as in the past by the barrier-of saline water (68%o) which w£3 present at the end of the former century. There was also a rise in temperature of the whole water column off the Israeli coast so that, the physico-chemical characteristics of the eastern Mediterranean became, in the former decade, more similar to those of the Red Sea, thus enabling the acclimatization of the Indo-Pacific species in the Levant Basin, OREN (1965).

The majority of the invertebrates of the Israeli coast are of Atlantic- Mediterranean distribution, reaching the Lusitanien and Mauretanian regions; though a majority of these reached the eastern Mediterranean, there exists a group of species which were not encountered east of Crete. Their absence from the Israeli coast is a fact proved in the course of the extensive benthos studies.

The distribution of isotherms at the surface of the area east of longitude 32° during July 1963, is such that an existence of a barrier to the penetration of pelagic larvae from the Levant Basin into the western Mediterranean may be suspected. The majority of benthic and invertebrates reproduce in the eastern Mediterranean during the summer months, and-consequently, the distribution of adults must be dependent on the hydrographical conditions prevailing during this season of the year.

The surface isotherms of June through September in the Levant Basin are passing in the north-south direction. This kind of temperature distribution may be a factor contributing to the limited distribution — especially of stenotherm inver- tebrate species. A suggestion was made that the absence of some species fro» the eastern Mediterranean but abundant in the Greek waters and Marmara Sea., is a result of the Nile flood, causing a considerable decrease in salinity during September- October, each year. It became evident.in view of the investigations carried out recently, OREN and KOMAROVSKY (1961) that the spreading out of Nile water is limited to a distance of about 10 km off shore and to a maximum depth of 40 -metres off the coast of Israel (isohaline 38%O). This would indicate that thé rate of survival of the larval stages may not only be affected by salinity, and that an important factor in the distribution of certain invertebrate species in the

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During the period 1947 - 1950, the temperature of the waters in the Levantine Basin was lowest in March -- 16.1°C -- and at the depth of 100 metres it dropped to 15.7°C. In 1955 and 1956, the sea surface temperature was higher by 1.5° as compared with the temperature of the coldest month (which is usually February) in 1949 and 1959, OREN (1957). The rise of temperature and the high salinity during the pre-Aswan Dam period made comparable the physical and chemical conditions of the Red Sea and eastern Mediterranean waters. It was concluded by OREN (1969) that the flow of the Nile was considerably reduced since 1965 as a result of the Aswan Dam operation; its influence was detected off Ashdod and off Haifa in September and October that year when the reduction of salinity

was negligible (38%O). During former years, the salinity was observed to drop to a value of 34.79 per mill. Maximum salinities were recorded close to 40 per mill, while during the Nile flow they reached a value of 31 per mill off Gaza, 34 per mill off Ashdod and 35-36 per mill off Haifa, OREN (1952). He stated further that "tremendous quantities of nutrients are brought into the sea by the Nile River, which add considerably to the productivity of these coastal waters".

The annual discharge of Nile water into the Mediterranean amounted to 35 billion m ; this figure was subject to fluctuation from year- to year. In a station close to the Rosetta mouth of the Nile, the salinity dropped to a value

as low as 28.75%O in 1962, ALEEM AND DOWIDAR (1967). In 1959 and 1960, a survey was carried out of the hydrographical conditions and plankton characteristics of the Israeli coastal waters during the Nile flood. The Zooplankton was found to be very rich and there was a mass development of certain organisms, e.g. Podon polyphemoides, in waters with lower salinities, OREN and KOMAROVSKY (1961).

2.1.1 Granulometric Analysis of Sediments

Grain-size distribution of sediments taken in the same area where ecological investigations were carried out is presented in Table 2.3 and fi£* (2.2). \ Two areas of the continental shelf were selected for sediment studies: Haifa Bay and Atlit-Caesarea. The Trask Sorting Coefficient

d75 and the percent!le value i «Elf * dT0" were calculated.

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Table 2.3

Percentage Composition of Sand, Silt and Clay in Sediment Samples Taken in the Area Atlit - Netanya

P e r c e n t a 8 ©

Depth (fathoms) Station Sand Silt Clay \

11 3 100 _ _ 11 4 100 - - 12 3 100 - - 12 20 100 - - 12 2 100 - - 12 1 100 - - 26 21 19.0 47.9 33.1 27 18 65.1 13.8 21.1 27 7 24.3 47.8 24.9 27 5 49.5 23.0 27.5 27 18 27.7 31.0 41.3 28 6 31.5 29.9 38.6 29 5 16.2 40.7 43.1 30 7-»- 6* 56.5 15.7 25.8 40 10 -*• 11* 4ß.O 18.6 33.4 40 9 20.6 41.5 37.9 42 10 35.5 29.3 35.2 42 9 •* 11* 30.6 33.6 35.8 43 18 27.7 31.0 41.3 50 6 20.3 46.3 33.4 55 - 60 9 18.6 36.4 45.0 100 9 10.3 43 j 3 46.4 100 13 8.7 43¿S< t 47.8

• Majority of sediment s&mples taken by mans of Emery and Petersen Grabs. *S«aple taken by means of dredge. Sand: 2 - 0.062 mm; Silt: 0.062 - 0.004 mm; Clay: <0.0004 mm - 9 -

The present data are complementary to the results of studies published previously, EtCRY and NEEV (1960); NIR (1961). The interpretations of the results obtained in the present studies can be made fro« fig. (2.2),in which a number of cumulative curves of sediments are presented. Two depth lines, parallel to the coast, of 10-12 fathoms and 25-28 fathoms between Atlit and Caesarea, are represented by stations 1,3,4 and 5,7,18,21 respectively.

The percentage composition of sand, silt and clay at different stations on the Israeli continental shelf is presented in Table 2.3. The percentage of each fraction by weight was determined for the following soil grades:- sand - 2 to 0.062 mm; silt - 0.062 to 0.004; clay - <0.004 mm.

As may be observed, the stations located at the 11-12 fathom depth line have pure sandy bottom. Stations situated at other depth levels are charac- terised by sediments composed of sand, silt and clay. At the depth lines 27-28 fathoms, the sand and silt are predominant, while at the 40-43 fathom depth level, the ratio of the three components is almost equal. The decrease in the amount of sand may be noticed starting with the 50 fathom depth (20.3%) reaching the lowest value at 100 fathom depth (8.7%) with almost equal values for silt and clay: 43.5 and 47.8 per cent, respectively. This situation is characteristic for the central section of our continental shelf (Atlit-Netanya). The amount of data is not sufficient to describe the sediment character in greater detail, therefore a series of samples was taken for further granulo- me trie studies and will be processed in future.

The importance of knowledge on the grain size distribution of sediments lies in the fact that quartz sand has a low inherent charge and a low ion exchange capacity as compared with silt and clay. Therefore, greater amounts of radioactivity can be associated with the last two components. The situation is clearly illustrated, representing concentration of nuclides: Ce-144, Ru-106, Cs-137, Zr-95, Co-60, Sr-90 in bottom sediments collected from the rivers in which activities were caused by the nuclear operations at Oak Ridge, FRIEND (1963).

*The grain-size distribution analyses of sediments was carried out in the Coast Study Division Laboratory, Israel Ports Authority.

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Gross beta radioactivity was measured in sediment samples of the Ligurian Sea (1963-68); maximum values in 1963 were 20-30 cpm/g dry sediment of the upper layers in the core samples and decreased to 10-12 cpm/g in 1968. The natural radioactivity was 8-10 cpm/g of sediment, SCHREIBER (1968).

The studies in ecology of marine organisms were carried out on the benthic invertebrates in order to obtain detailed information on the seasonal and geogra- phical distribution of the dominant species. The purpose of these studies is to determine the appropriate indicator organisms which can be used in measuring concentration of radionuclides in a marine environment. The majority of organisms collected in the course of the survey form an important link in the marine food chain being consumed by the demersal fishes. Their larvae are distributed in the water layers from the surface to the sea bottom and lead a planktonic life before they descend to settle down as adult benthic organisms.

The data available on the sediment character in the same stations where the benthic invertebrates live, will serve in future for analysis of the environmental conditions in reference to the distribution of these animals. The edaphic condi- tions, are the most important factor influencing the formation of benthic communities.

The topography of the continental shelf was described by EMERY and BENTOR (1960). The continental slope is gentle in the south, measuring 2.0°, steepening to about 8.5° in the north. The Israeli section of the continental shelf forms the transi- tion between the deltaic slope and a true continental slope, and its base merges gradually into the deep sea floor of the Levantine Basin.

The grain-size composition of the detrital sand beaches of the Israeli coast resembles the properties of sand from the Nile River which carries them along the northern coast of Africa and in the northern direction. Supplemental contributions from sea cliffs and seasonal streams of Sinai participate in the formation of detrital beach sands of Israel. The sand movement is controlled by the northward current, so that the fine grained detrital aand reaches Haifa Bay and past the northern border of Israel, EMERGY and NEEV (1960). The quantity of organic matter increases rapidly parallel to the depth, reaching a higher value in the south off Ashkelon than along the profiles between Nahariya and Ashdod. The values of 1.0 - 1.2 per cent of organic matter are characteristic for the depth starting with twenty fathoms. Irregular fluctuations are observed at various depths along all the profiles, NEEV (1965). - 11 -

2.2 Distribution of Marine Organisms

The distribution of species in the benthic biocoenoses were the objectives of study of animal populations of the sea bottom where the invertebrates are relatively static. They represent also the animals living on the substratum and those which dig relatively deep into the sediment composed of sand, silt and clay.

The abundance and distribution of various species of benthic invertebrates with respect to their habitats was studied in different areas of the Israeli continental shelf. The results of these studies combined with the knowledge of concentration factors in relation to fission products provided indicator species in radioactive contamination.

The stations for sampling of biota were established in the same area in Haifa Bay where the water samples were taken. (Map I).

The second area which was intensively studied and from where a number of samples were taken for radionuclide determination was Atlit-Caesarea (Map II). Sampling was carried out along the Ashdod profile* further south, Gaza and off El-Arish, and later, north of Sinai (Map III).. The total number of bottom samples collected starting December 1966 to February 1970 was 544. During the period preceding the present investigation, 362 samples of benthos from the above- mentioned areas were taken within the regular program of ecological studies. These preliminary data serve as complementary material for the present investigation.

At the first stage of the investigation the percentage composition (per number and weight) of the main systematic groups in random samples was calculated for depth lines of 10-12, 30-35 and 40-42 fathoms covering the station grid off Atlit-Caesarea.

From these studies it may be observed that decapods, molluscs and echinoderms form the majority of the biomass. The polychaetes which form an important item in the food chain are not represented in the right proportion due to the selectivity of the gear: dredge and beam trawl.

In Haifa Bay, an ecological survey was carried out in three areas with different edaphic features of the substratum: sand, rocks and silt clay. - 12 -

It is evident that in the sandy sediments the greatest biomass was obtained for the molluscs: Gastropoda and Lamellibranchiata, while Polychaeta, Decapoda and Echinodermata formed in several samples taken in winter 1966/67 not more than 1-3 per cent of the total biomass. In areas where the sediment is rocky the worms (polychaetes and sipunculoids) and molluscs are predominant. On silt-clay sediments the anthozoans and echinoderms form the largest biomass though crus- taceans and molluscs are present in moderate quantities.

The characteristically dominant species in Haifa Bay in samples taken in November, December 1966 and January, May 1967, may be mentioned:

Substratum - sand: Polychaeta: Hermodice carunculata; Mollusca: Aloidis gibba, Cerithium recurvum, Aporrhais pespelicani. Substratum - silt-clay: Anthozoa: Pennatula rubra, Oecapoda: Parapenaeus longirostris; Mollusca: Murex brandaris; Echinodermata: Astropecten aranciacus, Brissopsis lyrifera.

The survey of the continental shelf disclosed the presence of macrobenthic communities situated within zones parallel to the coast, at different depths. Although a large quantity of data on the distribution of invertebrates were accu- mulated in the area Atlit-Netanya during recent years (1965-1968), the comparison of the biocoenosis is presently based on a number of randomly chosen profiles. These are representative for the total continental shelf of Israel: Alexander River and El Arish.

The sand bottom community of the Alexander profile (see Map II, Stations: 34-45) at the 8-12 fathom depth comprises the following dominant species: the alga: Caulerpa scalpelliformis; Decapoda: Diogenes pugilator, Portunus hastatus; . Mollusca: Nassa mutabilis, Natica josephina, Venus gallina, Mactra corallina, Cardium tuberculatum; Echinodermata: Echinocardium cordatum, Ophiura texturata, Astropecten pentacanthus.

On comparing this community with the corresponding one of the same depth line (5-8 fathoms) off El-Arish, it appears that the dominant species are identical. However, at the depth of 12 fathoms, the composition becomes entirely different, indicating that the sand-silt biocoenoses of the northern section of the coast approach very close the coast off El-Arish. This is mainly attributed to the fact that the sediment characteristics at corresponding bathymétrie lines in these distant areas are different. - 13 -

At the depth of 12 fathoms we find on the El Arish profile a biocoenosis which roughly corresponds to that of the 25-30 fathom depth off Alexander River. The characteristic.Indo-Pacific species in this assembly are: Charybdis longicollis and Venerupis undulata. The bathymétrie distribution of Charybdis has been mentioned in the study of the Rubin River profile (1960-1962), which corresponds to sand-silt sediments. It was noticed that this Indo-Pacific species is abundant in the area containing 50 - 75 per cent silt and clay, where a relatively high percentage of organic matter exists.

The next Indo-Pacific species, Venerupis undulata, off El Arish is characteri- stic for the area of 5-20 fathom depth, while its distribution at the northern section (see Stations 8-13 off Rubin) GILAT (1964) is limited to the 20 fathom depth line, not approaching the coast where sandy sediments prevail.

The sea urchin, Schizaster canaliferus is an indicator of sand-silt biocoe- nosès in Haifa Bay, at the depth of 20-25 fathoms. This species is present in the parallel biocoenoses at the Alexander River profile and in the Rubin area, GILAT (1964). Its distribution extends into deeper waters, reaching off El Arish the depth of 30 fathoms, where it overlaps with the distribution of the echinoids, Echinocardium cordatum and Brissopsis lyrifera, which are indicators of sandy and silt-clay sediments respectively. The dominance of Echinocardium cordatum, an indicator of the sand-silt biocoenoses of shallow depths, where the percentage of sand is high, can be also observed in the southern section of the continental shelf.

It has been observed that the distribution of the offshore population is independent of the pattern of sediment distribution. E. cordatum persists in the area where organic matter is scarce, and appears in concentric patches, stable in position and shape. It may be postulated that the larvae aggregate at the time of settlement during their planktonic stage before the metamorphosis takes place. These aggregations during June, July and August correspond to the breeding season of Echinocardium on the Northumberland coast of England, BUCHANAN (1966).

A conclusion was drawn that various species or races of spatangoids which were deposit feeders consuming the organic matter in the sediment, have specialized feeding mechanisms. These feeding mechanisms have a possible bearing on the distribution and growth rate of the species. - 14 -

The profile off El Arish was chosen as an indicator of the benthos characteris- tics of the southern section of the shelf. The sand-silt sediment characteristic for the depth of 5-8 fathoms inhabits a population rich in Polychaeta, Scaphopoda, Tanaidacea, Decapoda, Mollusca and Echinodermata. In some samples, the presence of Porifera and Bryoza was noticed. The survey at these depths was carried out in July 1968 and August, September 1969. The benthic community may be characterised as : Diogenes pugilator - Venus gallina.

There are several species which deserve attention because their distribution is limited to this area: Charybdis merguiensis, Eledone moschata, Loripes lacteus. In this community, the Indo-Pacific species were as follows: Squilla massavensis, Metapenaeus monoceros, Myra fugax, Portunus pelagicus, Charybdis longicollis, Venerupis undulata. The species Squilla massavensis is natant and spreads into deeper waters and can be regarded as a member of several biocoenoses. The presence of Hydroides norvegica and H^ lunulifera indicates that hard substratum composed of gravel is present in the area. The changes in the substratum are gradual, which results in the overlapping of parallel communities to the coast line at the depth of 5-10 fathoms. However, some species are restricted in their distribution. At slightly deeper waters extending between 8 and 10 fathoms, the following species become abundant: Sternaspis scutata, Metapenaeus monoceros, Alpheus glaber, Charybdis longicollis, Venerupis undulata, Ophiopsila aranea.

The distance between the bathymétrie lines of 5,8,10 and 12 fathoms are at the average, one to two nautical miles. It is worth mentioning that the composition of species changes with short distances - most probably because of the substratum characteristics. This fact becomes more evident when the biocoenoses of the 12 fathom depth is studied. There is no doubt as to the increase in biomass of Echinocardium cordatum, the number of specimens of which attains hundreds per tow, in both beam trawl and dredge. The same community exists about two nautical miles further to the north of the El Arish profile, as can be judged from the sample taken at 15 fathoms, August 1969, by means of dredge and beam trawl. The composi- tion of species changes little at the 18 fathom line, where in addition to the above- mentioned species the following appeared: Squilla mantis, Upogebia tipica, Dorippe 1anata, Aporrhais pespelicani, Nucula nucleus, Natica millepunctata, Natica flammulata, Tellina sp., Astropecten sp., Hemichordata. - 15 -

The area between 20-25 fathom depth is of about two nautical miles width parallel to the coast line. The analysis of the biocoenoses hfis shown a variety of species as compared with that found in shallower waters and a richness in the number of invertebrates. The composition of species at the 30-40 fathom depth off El Arish (August, November 1969) indicates that the biocoenoses is charac- teristic for the silt-clay sediments of the eastern Mediterranean. The dominance of the following species in the community is evident: Sabella pavonina, Aloidis gibba, Antedon mediterránea, Brissopsis lyrifera.

There are a number of species of macrobenthos which accompany the quantitatively dominant organisms; the characteristic ones are as follows: Pennatula rubra, Upogebia tipica, Processa canalicutata, Cardita trapezia, Cassidaria echinophora.

The diversity of species in this area is much less evident than at the 20-25 fathom depth. The less important species, but still characteristic for the community are: Alpheus glaber, Parapenaeus longirostris, Macropipus depurator, Charybdis longicollis, Cardium paucicostatum, Natica flammulata, Nucula sulcata, Philine aperta and Hemichordata.

The biomass of benthic invertebrates calculated per 1000 m in which the representative species are indicated is compiled in Table 2.4. The percentage of organic matter of the indicator species of the continental shelf is presented in Table 2.5. - 16 -

Table 2.4 2 Dry organic matter in grans per 1000 m calculated for representative species of benthic invertebrates

Sample Depth Per cent Net weight Dry organic no. (fathoms) dry organic in grams matter per natter per 1000 1000 m2 B2

1518 12 1.5 0.13 Pennatula rubra 1445 40 8.8 51.7 4.55 1545 40 44.3 3.89

1566 12 9.5 2.05 Diogenes pugilator 1567 12 21.6 17.3 3.73 SLMB-141 12 24.5 5.29

Portunus hastatus 1581 12 12.3 6.2 0.77 Charybdis longicollis 1619 12 12.3 325.5 40.03 Macropipus depurator 1486 27 13.1 4.0 0.52 Myra fugax 1544 40 14.1 26.3 3.70 Dorippe lanata 1506 70 10.3 9.7 1.00 Parapenaeus longirostris 1449 40 16.8 134.0 22.50 Metapenaeus nonoceros 1507 12 16.8 3.5 0.60 Galathea intermedia 1478 30 6.3 1.6 0.10 Aporxhais pespelicani 1619 12 6.0 16.2 0.97 Glycymeris pilosus 1566 12 4.6 2.4 0.11 Nactra corallina 1567 12 5.3 6.8 0.36 Aloidis gibba 1652 12 5.7 4.5 0.25 Pheline aperta 1508 12 14.0 3.5 0.49 > 1482 27 60.5 1.45 Brissopsis iyrifera 1445 40 2.4 116.6 2.79 1545 40 197.6 4.74

1530 12 60.0 0.90 Echinocardium cordatum 1566 12 1.5 104.5 1.56 1567 12 43.0 0.64

Ophiura texturata 1507 12 2.0 1.6 0.03

Ï I - 17 -

Table 2.5 Percentage of dry organic matter in benthic invertebrates

Species Dry org. Wet Dry Ash Dry/ Ash/ No. of matter (grams) Wet Dry Spec. Alcyonium palmatum 5,2 64.5 10.0 6.6 15.5 66.0 (6) Stemaspis scutata 4.6 10.8 1.9 1.4 17.6 73.6 (21) Hermione hystrix 9.9 2.1 0.5 0.3 22.2 53.2 (10) Hyalinoecia tubicola 18.0 0.2 0.06 0.02 30.7 41.1 (14) Pennatula rubra 8.8 51.0 10.8 6.3 21.1 58.3 Pennatula rubra 8.0 708.0 132.0 75.7 18.6 57.3 Pennatula rubra 10.2 211.2 41.8 20.2 19.8 48.0 (30) Squilla massavensis 10.7 718.2 103.9 26.6 14.4 25.1 (25) Squilla mantis 19.2 S5.6 14.2 3.5 25.5 24.6 - Squilla mantis 13.0 44.1 7.9 2.2 18.0 27.8 - Squilla mantis 12.4 258.6 39.7 7.4 15.3 18.6 - Pontocaris cataphracta 13.2 0.4 0.07 0.02 16.8 26.0 Parapenaeus longirostris 16.8 407.7 82.1 13.5 20.1 16.4 (138) Penaeus japonicus 24.0 685.0 200.0 34.6 29.2 17.3 Penaeus semisulcatus 18.0 746.5 150.1 17.0 20.1 11.3 Penaeus semisulcatus 21.8 217.6 53.8 6.2 24.7 11.5 Penaeus kerathurus 20.0 127.5 29.8 4.5 23.4 15.1 Penaeus kerathurus 24.1 22.8 6.4 0.9 28.0 14.0 Galathea dispersa 6.3 0.17 0.04 0.03 24.8 74.3 Diogenes pugilator 21.6 6.5 2.3 0.9 35.3 39.1 Charybdis longicollis 12.3 135.0 37.5 20.8 27.7 55.4 (19) Macropipus depurator 13.1 3.5 0.9 0.4 25.2 48.3 Dorippe lanata 10.3 7.7 1.7 0.9 22.0 52.9 Myra fugax 14.1 348.5 147.8 98.5 42.4 66.6 Eurynone áspera 18.1 0.5 0.2 0.1 40.6 S6.6

»- S '"S

'J: '','--.-j _: '\í\~, ;,' '"."', '_'-'-.'-, ,' •"

"-*1 ~ ; ''"':

- 18 -

* Table 2.5 (cont*d)

Dry org. Dry/ Species Wet Dry Ash/ No. of matter (grams) Ash Wet Wet Spec. ! Aporrhais pespelicani 14.6 0.8 0.3 0.2 40.1 63.7 _

22.0 6.8 1.9 21.0 T : Nassa mutabilis 0.4 27.9

Glycyoeris pilosus 12.1 29.6 4.3 0.7 14.4 16.2 -

Cardium echinatum 8.7 1.0 0.1 0.03 11.7 26.2 - : Hactra corallina 13.8 . 10.8 1.9 0.4 17.5 3.7 - Aloidis gibba 8.3 1.2 0.3 0.2 25.0 66.6 (100) Cerithium kochi 21.5 5.1 2.8 1.7 55.0 67.0 - Sepia officinallis 19.6 4.460 946.0 69.1 21.2 7.3 (30) Sepia(shell) 6.5 107.0 51.1 44.1 47.7 86.3 (13) Loligo vulgaris 19.1 940.0 222.6 42.6 23.6 19.1 (21) Sepiola rondeleti 13.0 3.6 0.5 0.03 14.0 7.1 (2)

Astropecten irregularis 6.2 23.83 11.12 9.65 46.6 86.8 - Antedon mediterránea 7.0 71.8 20.6 15.6 28.6 75.6 - Astropecten aranciacus 11.5 270.0 122.7 - 45.4 - - Echinaster sepositus 11.0 76.0 21.2 12.8 28.0 60.4 -

\ Echinocardium cordatum... 1.5 59.5 31.8 30.9 51.8 97.1 -

| Brissopsis lyrifera 2.4 353.3 128.9 120.3 33.6 93.3 (80) i rj. ——

! ¡i g s •

- -

| - - H • í ' - 19 -

Biocoenoses of the Levant Basin

The sandy bottom (depth 10-20 m) community, Echinocardium-Venus of the boreal waters, is also present in the eastern Mediterranean. In Haifa Bay, this community is modified to a large extent due to the abundance of other species, e.g. Pontocaris caraphracta, Diogenes pugilator, Cardin« paucicostatum, Tellina distorta, Amphipholis squamata, Astropecten bispinosus, Herdaania «onus.

The change from pure sandy bottom to sand-mud in Haifa Bay causes the appearance of species, e.g. Pagurus spinimanus, Dorippe lanata, Macropipus depurator, Myra fugax, Aporrhais pespelicani, Antedon Mediterránea, Schizaster canalíferas, Astropecten irreguiaris, Ophiura texturata.

The Brissopsis lyrifera - Amphiura chiajei community of the muddy substra- tum of deeper water (80-260 m) is characterized by the presence of Pennatula rubra, Sternaspis scutata, Sábella pavonina, Parapenaeus longirostris, GILAT (1964).

A comparison of the communities in the eastern and western Mediterranean was discussed by GILAT (1964), based on studies carried out in the Adriatic Sea and on the continental shelf of Israel. The studies completed recently GILAT (1966) in the Ligurian Sea (French Coast) permit a further comparison of the western and eastern Mediterranean basins. In the eastern Mediterranean off the Israeli coast on sandy bottoms, the community of Venus gallina is present but the shells of Nassa mutabilis (a species of secondary importance) were mostly found occupied by the decapod Diogenes pugilator. Another community on sand-muddy bottoms parallel to that of Turritella comwunis in the Adriatic Sea, is the community of Brissopsis-Awphiura of the Israeli coast with the polychaete Sabella pavonina" at the southern section of the coast. This community is present in the Bay of Roquebrune represented by the polychaete S;_ pavonina; crustaceans, Scalpellum vulgäre, Inachus dorsettensis; echinoderm, Cucumaria tergestina and tunicate, Diazona violácea. B. lyrifera is less significant in the same community as compared with the eastern Mediterranean. - 20 -

On compiling the community of Schizaster canaliferus - Echinocardium cordatum off the Israeli coast with that of the Bay of Roquebrune, we find in the former (Bay of Haifa] a composition of species which correspond to a biocoenosis typical for both, terrigenous and detrital muds of the western Mediterranean.

The majority of Britrean species which penetrated the Suez Canal beca established in the eastern Mediterranean and form thriving populations, presumably due to the tropical conditions prevailing there. Therefore both, the species of Indo-Pacific origin and those of the Atlantic-Mediterranean distribution, are dominant in various communities of the Levant Basin. The Schizaster-Echinocardium community, characteristic for the Northern Atlantic, has been investigated off the Israeli coast, as a part of benthos studies at two different periods with an interval of about ten years between them. These studies proved that although Schizaster remained a dominant species, the community underwent some changes in the species composition. The pene- tration of the Indo-Pacific decapod, Charybdis longicollis which was not observed on the Israeli continental shelf previously, became a characteristic feature of this biocoenosis. Communities of filter-feeding crabs were mentioned as characteristic of tropical waters which mainly feed on detritus of planktonic origin in the sediments, THORSON (1957).

PERES and PICARD (1958) studied the biocoenoses in the Aegean Sea and arrived at a conclusion that there exists a uniformity of the communities in the Mediterranean Sea in this area and to the west. They have mentioned the presence of a typical community composed of the dominant species Venus gallina, and Nassa mutabilis on the sand-muddy bottom of the circalittoral shelf.

The polychaetes, Sternaspis scutata, Maldane fflebifex, and the echinodems, Brissopsis lyrifera, Amphiura chiajei were classified as representative invertebrates of the bathylittoral shelf in the western Mediterranean, PERES and PICARD (1964). In the eastern basin they exist in shallower waters also at the depths of approximately 20 m. Their distribution may be a function of the sediment character and the hydrographical conditions which vary to a large extent from the western to the eastern part of the Mediterranean. - 21 -

The distribution of several species of Portunidae in the eastern Mediterranean is peculiar, showing that both the Indo-Pacific and Atlantic species (not common in the western Mediterranean) may thrive there. Callinectes sapidus is an example of a species of typical Atlantic distribution which possibly was transferred to the eastern Mediterranean by ships or other- wise, and became at the Israeli coast, one of the most common species sharing the biotope of sandy bottoms with the Indo-West Pacific crab Portunus pelagicus HOLTHUIS and GOTTLIEB (195S). The communities off the Israeli coast in the Mediterranean on the sandy and sand-muddy substratum have, to a certain extent, a similar composition of species which corresponds to the biocoenosis described from the western basin. The rocky substratum is, however, formed by different elements in the Bay of Roquebrune, of which the corals» Caryophyllia clavus, Paramuricea clavata and Eunicelia cavolini and the Bryozoa, Myriozoum truncatua, Porelia concinna, and P. cervicornis are important components. The substratum covered with Peyssonnelia polymorpha which inhabits a special biocoenosis off Marseilles, CARPINE (1958) has never been observed in the Levant Basin. The differences in the formation of the hard substrata in Various regions of the Mediterranean, can be explained mainly by the differences in the hydrographical conditions which are also the main reason for the variability, in the productivity and in the biomass of the benthic invertebrates.

It is a characteristic feature of the sea bed in the Haifa Bay that the alga, Caulerpa scalpelliformis forms extensive sub-marine prairies replacing here the common species in the western Mediterranean, Ç^ proliféra which is a resistant organism to marine pollution in the Ligurian Sea. C. scalpelliformis is found in sandy-mud areas of the Haifa Bay but its abundance in the southern section of the Israeli continental shelf has not been observed. This biotope corresponds to the biotope of Posidonia oceánica in the western Mediterranean. The rocky area formed by the coral Dendrophyllia is covered by the aiga, Halimeda tuna. Another association of calcareous algae has also been described in Haifa Bay composed of Lithothamnium, Melobesia and Peysonnelia spp. - 22 -

There is a similarity in the composition of the biocoenoses of the muddy sediments of the Israeli and French coasts in the Mediterranean. As an important feature of the parallel biocoenosis in the western Mediterranean it should be pointed out that the holothurians, Holothuria spp. and Stichopus regalis and the ascidian, Diazona violácea, are dominant here; these do not exist or are very rare off the Israeli coast. The scaphopod, Dentalium inaequicostatua, abundant in the detrital sediments of the western Mediterranean was not recorded in the Levant Basin.

The character of the substratum in the studied areas is given here as an example of the biotopes characteristic for a coastal area where the sand-Middy sea bed with rocky formations exists. A similar biotope in various geographic regions is inhabited by level bottom parallel communities in which the dominant genera are identical, but the species vary, THORSON (1957). The rocky bottom communities, however, are characteristic for geographical regions. It has been demonstrated for various seas that the character of the substratum is an important factor influencing the composition of the level bottom communities. In the coastal area the hydrographical factors may be predominant, e.g. temperature, salinity and light intensity.

The absence of some typical Atlantic-Mediterranean species from the Levant Basin is a characteristic feature which needs further investigation. There is a relatively long list of species which are common in the western Mediterranean, but were never encountered in the benthos collected at the Israeli continental shelf, e.g. Parapandalus pristis, Crangon crangon, Palinurus vulgaris, Nephrops norvegicus, Cancer pagurus, Spatangus purpureus, Echinus acutus, Astropartus mediterraneus.

The low salinities during the Nile flood and subtropical temperatures were mentioned as the most important factors in the distribution of the invertebrate larvae which being pelagic, are transported with the water masses before reaching the substratum.

It seems that the character of the substratum is a secondary factor in the distribution of species in relation to the zoogeographical boundary dividing the Mediterranean into eastern and western basins. - 24 -

The affinity of benthic invertebrates to the edaphic conditions governs their, distribution provided that the other environmental parameters such as temperature and salinity are not different to a large extent. A similar biotope in various geographical regions is inhabited by parallel level.bottom communities in which the dominant genera are identical, but the species vary THORSON (1957). The biocoenoses of the Israeli continental shelf can be distinguished by the species distributed in zones parallel to the coast. The area closest to the coast has a sandy bottom which reaches a depth of 20 metres on the average. The characteristic species of this community are as follows: Decapoda: Diogenes pugilator, Portunus hastatus; Mollusca: Cerithium recurvum, Nassa mutabilis, Natica josephina, Mactra corallina, Aloidis gibba, Venus gallina, Cardium tuberculatum; Echinodermata: Echinocardium cordatum, Astropecten irreguiaris pentacanthus.

In the Bay of Haifa this community is modified and composed of the following species : Hermodice carunculata, Pontocaris caraphracta, Diogenes pugilator, Cardium paucicostatum, Tellina distorta, Amphipholis squamata, Astropecten bispinosus, Herdmania momus.

The above-mentioned species are of Atlantic-Mediterranean distribution except the tunicate Herdmania momus which passed through the Suez Canal from the Red Sea and is very abundant on sandy bottom usually associated with the alga Caulerpa scalpelliformis, PERES (1958).

In the rocky substratum which forms patches within the sandy bottom at the depths of 22-25 metres, in Haifa Bay, polychaetes belonging to the families of Syllidae and Eunicidae are very abundant. They are represented by a few genera with a number of species which are either cosmopolitan or Atlantic-Mediterranean: Syllis spongicola, S^ gracilis, S_¡_ armillaris, S¿_ variegata, S¿_ arnica, Syllis (Ehlersia) cornuta, Trypanosyllis zebra; Eunice vittata, E¿_ torquata; Luabrico- nereis impatiens, j^ coccinea, L^ gracilis, Staurocephalus kefersteini, FAUVEL (1957). - 25 -

The biocoenosis of sand-silt bottom in the area Caesarea-Netanya at the depths of 20-50 metres is relatively rich in species, the following being dominant: Polychaeta: Hydroides norvegica; Decapoda: Pontocaris cataphracta, Pagurus cuanensis » Galathea intermedia, Macropipus depurator, Myra fugax; Stomatopoda: Squilla massavensis; Mollusca: Aporrhais pespelicani, Cerithium recurvum, Aloidis gibba, Cardium paucicostatum, Leda pella; Echinodermata: Antedon mediterránea, Echinocardium cordatum, Astropecten irregularis penta- canthus, Ophiura texturata.

Among the above-mentioned species, Squilla massavensis and Myra fugax are of Indo-Pacific origin. This community is relatively rich in the number of species and specimens per unit of sea bottom. This is primarily due to the quantity of food available for the invertebrates, which are mostly suspension or deposit feeders utilizing the detritic matter. The percentages of organic matter in sediments of the Bat Yam-Ashdod area were determined and it was shown that the highest value (1.77) was present at the depth of 36 metres with a characteristic sand-silt bottom and the lowest value (0.04) was present at the depth of 9 metres, GILAT (1964).

A relatively small number of samples taken off the northern coast of Sinai proved that the sand-silt biocoenosis which extends in this area to a depth of 50 metres, is almost identical with the parallel biocoenosis of the Israeli continental shelf. In July 1968, samples of macrobenthos were taken in the areas of Wadi el Hesi, £1 Arish, El Burg, and in October 1968 off the Bardawil lagoon. The relatively small number of samples collected in the southern region permits a comparison of the communities in the eastern section of the Levant basin to a limited extent. It should also be kept in mind that the grain size composition of the sediments in relation to depth is different because of the deposit of particles due to the flow of the Nile into the Mediterranean.

However, it may be instructive to present at this stage of investigation a preliminary list of the common species in dredge and beam trawl samples off Sinai, at the depth of SO metres: - 26 -

Polychaeta: Sternaspis scutata, Melinna palmata, Terebellides stroeai; Decapoda: Parapenaeus longirostris, Synalpheus laevimanus, Alpheus glaber, Pontocaris cataphracta, Macropipus depurator, Dorippe 1anata; Mollusca: Aporrhais pespelicani, Aloidis gibba, Natica millepunctata, N. flammulata, Nassa mutabilis; Echinodermata: Antedon mediterránea, Brissopsis lyrifera, Schizaster canaliférus, Astropecten? spinulosus, Amphiura chiajei.

The typical communities of the eastern and south-eastern regions of the Levant Basin were not located in the Famagusta and Akrotiri Bays on the eastern section of the continental shelf of Cyprus. The Indo-Pacific species which form dense populations on our continental shelf were not located at this stage of investigation off Cyprus. There is an indication that in spite of the very close vicinity of this island to our coast, the environmental conditions are much more favourable for the survival of the typical Atlantic Mediterranean invertebrate fauna. The list of species taken in a dredge sample, at the depth of 30 fm., in February 1968 in Akrotiri Bay is given below: Polychaeta: Stenelais minor, Syllis cornuta, Nereis irrorata, Glycera tesselata, Eunice vittata, Staurocephalus rubro vittatus., Chrysopetalum debile, Terebellides stroemi. Decapoda: Paguristes oculatus, Galathea intermedia, Scyllarus arctus, Inachus thoracicus, L¡_ dorsettensis, Ethusa mascarone, Eurynome áspera, Ilia nucleus. Mollusca: Propeamussium hyalinum, Arca láctea, Pectén glaber. Echinodermata: Psammechinus microtubercularus, Echinocyamus pusillus, Ophiomyxa pentágona.

The typical communities of the eastern regions of the Levant Basin which include Indo-Pacific species were not found off Cyprus. On comparing the invertebrate fauna of the Israeli coast with that of Cyprus a close similarity is found with respect to Atlantic and endemic elements exclusively.

Ben-Eliahu (1969). - 27 -

Indo-Pacific Fauna

The penetration of the Indo-Pacific invertebrates into the eastern Mediterranean was observed previously for various systenatic groups, STEINITZ (1929).

The studies carried out by FAUVEL (1957) on polychaetes suggest that at least one species, Rhodine loveni, has presumably penetrated the Suez Canal. The polychaetes on the continental shelf of Israel are conposed mainly of cosmopolitan species.

The decapods form the most outstanding group among the Indo-Pacific invertebrates established in the Levant Basin, HOLTHUIS and GOTTLIEB (1956; 1958); LEWINSOHN and HOLTHUIS (1964). The most abundant among the Decapoda are: Penaeus japonicus, P. semisulcatus, Metapenaeus monoceros, M. stebbingj., Leptochela pugnax, Automate branchialis, Portunus pelagicus, Charybdis longicollis. These have not been reported from the western Mediterranean, the Aegean Sea being the western limit of their distribution for most of the Indo-Pacific invertebrates. None of them was disclosed in the course of the extensive studies carried out in the Adriatic Sea, VATOVA (1949); GAMULIN-BRIDA (1962).

The penetration of the Eritrean species to the western Mediterranean has been observed only in a few cases; the distribution of Indo-Pacific species is thus mainly restricted to the area east of Crete.

The Eritrean species: Penaeus japonicus, P. semisulcatus, Metapenaeus monoceros and M. stebbingi were found east of longitude 32°E, in the vicinity of the Suez Canal, at the continental shelf of Israel, Syria and in the Bay of Alexandretta (Turkey). Their restricted distribution must be governed by the hydrographical conditions which are of a subtropical character in the Levant Basin.

Of the 6 species of Alpheus found at the Israeli coast, 3 are of Atlantic- Mediterranean and 3 of Indo-Pacific origin. The species Automate branchialis - 28 -

(Alpheidae) of Indo-Pacific origin was only found on the Israeli continental shelf.

The species of Portunidae, Charybdis longicollis, of Indo-Pacific origin is also abundant on the continental shelf of Israel and found exclusively east of the Suez Canal.

A number of molluscs was reported as being of Indo-Pacific origin, HAAS (1948) of which the most abundant is Pteria occa. Modiola glaberrima Venerupis undulata and Cerithium kochi (altogether 32 species were identified by Drs. Barash and Danin as being of Indo-Pacific origin) during the recent survey on the Israeli continental shelf. Most of tfe molluscs dominant in the level-bottom communities are of Atlantic-Mediterranean distribution.

Of the echinoderms, several species, e.g. Ophiactis savignyi, Amphioplus laevis were mentioned as being of Indo-Pacific origin, TORTONESE (1954). The as ci di ans, Diazona violácea and Halocynthia papulosa which are common in the Bay of Roquebrune (Ligurian Sea) on the sand-muddy bottom, were not encountered off the Israeli coast. However, the abundance of the species, Herdmania momus, of Indo-Pacific origin has been observed in the sand-muddy bottom community in Haifa Bay, PERES (1958).

The Mediterranean Sea does not constitute an independent region from a bio-geographical point of view, but has a relationship with the Lusitanian and Mauretanian regions of the eastern Atlantic. The percentage of species of different origin is summarized by PERES (1967) for Hydroidea, Decapoda, Echino- dermata and Ascidiacea. It is pointed out that the proportion of endemic species within the above-mentioned taxonomic groups increases with the decreasing mobility of the invertebrates. This is certainly true for the adults, their migration being limited to a larger extent than for the larval stages, the majority of which are pelagic. The assumption is that the redistribution of the species within the benthic communities takes place mainly during the larval development before the metamorphosis. Though difficult to prove at this stage of study, the penetration of larval stages of. Indo-Pacific species through the Suez Canal, depends on their survival rate during the migration period.

#•••- - 29 -

The problem of migration from the Red Sea into the Mediterranean and vice versa was recently discussed by STEINITZ (1967,1968). The role of Eritrean species in the biogeography of the eastern Mediterranean is not only measured by their mere presence in the area but by the extent to which they have formed dominant populations. It may be stressed that the groups Decapoda (33 species) and Mollusca (20 species) are the most common invertebrates among the imaigrants (84 species excluding Pisces). As mentioned above the main reason in the dominance of certain organisms is their tolerance to the salinity and temperature changes when passing from one water mass into another. It has already been mentioned that the salinity near the bottom of the Suez Canal has been reduced from 52 per mill to 43 per mill within the last four decades, PERES (1967).

The migration of Indo-Pacific species in the Mediterranean Sea deserves attention when dealing with the ecology of the species once they passed through the Suez Canal. There seems to be a limit to their distribution in the western direction which can be tentatively located at the longitude of 30°E, with some exceptions, e.g. Portunus pelagicus and Myra fugax, which were taken in the western Mediterranean« It is also worth mentioning that the most common species of Indo-Pacific Penaeidae and other invertebrates caught in the trawl net off the Israel coast were not encountered in the Bay of Sirte (Lybia), in August 1956, where a fishing survey was carried out, though a variety of Atlantic and endemic invertebrates were collected.

There is no doubt that the currents are the most efficient way of transport for the invertebrate larvae. The larvae may survive in the new environment meeting the hazards of temperature and salinity fluctuations, if their food demands are satisfied. The geostrophic circulation, at the depths of 20 and 500 metres calculated in relation to the surface, favours the distribution of the larvae in the north-eastern direction along the coasts of Lebanon, Syria and the Anatolian coast of Turkey, The spreading of Indo-Pacific species into the Aegean Sea seems to be limited as the available records refer to Teleostei. The rare occurrence of the Red Sea immigrants in the. waters of Cyprus is probably due to the fact that larval stages must be swept over the distance of about 200 miles from an area where the isotherm of 28° C is located to an area opposite Faaagusta Bay with an isotherm of 20°C, at the depth of 20 metres, OREN aid ENGEL (1965). - 30 -

The migration of benthic invertebrate species is a slow phenomenon created by the displacement of a population randomly with a water mass moving out from the area where the parental stock is living on the bottom. This may be limited in most cases to neritic waters only because of the short survival period of the larvae before they reach the bottom for the metamorphosis.

The preliminary survey of the macrobenthos in the waters off north Sinai indicates that some of the typical Indo-Pacific species which were previously reported from Haifa Bay such as the polychaete, Rhodine.loveni, FAUVEL (1957) and Ophiactis savignyi, TORTONESE (1957) are abundant in the level bottom communities off Sinai. The decapod, Metapenaeus monoceros was also taken in the above-mentioned area.

•'-' -fi' - 31 -

Method and Experimental

3c1 Sampling of Sea Water and Biota

3.1.1 Sea Water

The study of radioactive contamination of marine environment and biota involves qualitative and quantitative determinations for radio- nuclides of biological interest, The purpose of such an investigation is to determine the rate of passage of radionuclides through the food chain to the human organism in subtropical conditions prevailing in the eastern Mediterranean. The Levantine Basin of the Mediterranean is characterized by high temperatures and salinities which are typical for a tropical area. These are the cause of survival and development of numerous Indo-Pacific organisms which penetrate from the Red Sea through the Suez Canal into the eastern Mediterranean. It is there- fore of interest to determine concentrations of radionuclides uptaken by the endemic as well as the Indo-Pacific species at various levels of the food chain.

In the course of this study, indicator organisms were used in measuring the concentration of radionuclides in marine environment. Attention was paid to the effect of organisms on the distribution of elements in the sea. The elements, of which a large proportion passes through the organisms, will thus undergo a modification in their spatial and seasonal distribution in the water and sediments.

The dilution and dispersion of radionuclides have a special significance in the eastern Mediterranean due to the effect of the Nile Flood which causes the accumulation of large masses of fresh water during a certain season of the year. The upwelling and vertical mixing have an effect cm the distribution of radioactive nüclides The Levantine Basin of the Mediterranean is characterised by high temperatures and salinities which are typical for tropical areas> and the productivity is relatively low as conpared with other areas. The eastern Mediterranean is inhabited by a characteristic - 32 - flora and fauna of Atlantic and Indo-Pacific origin. Species which penetrate through the Suez Canal are continuously changing the balance in the existing animal communities. This dynamic aspect of marine ecology poses problems which are unique in the oceans. Thus a variety of food chains exists, which is characteristic for tropical and sub- tropical seas, and which is liable to constant periodic fluctuations. As a result of this, any radionuclide entering this environment will have various possibilities of passage through these chains before reaching the edible fishes and invertebrates.

In the course of this investigation a planned sampling of the sea water sediments and organisms in a grid of stations on the continental shelf, was undertaken.

(i) Spatial Sampling; Sampling at various depth levels in relation to thermocline, Nile water distribution, upwelling and other mixing processes on thé continental shelf. The stations grid to be determined mainly according to varia- bility of the sea bottom structure.

(il) Seasonal Sampling; The sampling is generally planned to be carried out at monthly intervals. However, within the period of rapid changes in the characteristics of the environ- ,.••'' ment and composition of the benthos and nekton, special attention was given to the sampling procedure.

The collecting of biological samples was carried out at various seasons including occasionally, periods of reproduction of benthic invertebrates, as well as at seasons of the increased abundance of certain indicator species of pelagic and demersal fishes.

Water samplers, collecting 5 liters of sea water were used by CORCORAN and ALEXANDER (1964), constructed from PVC and equipped with reversing thermometer mechanism. A similar sampler collecting 30 liters of water was used in this study. Sediments are collected by means of the Peterson bottom grab or a dredge which is also used for collecting the benthic organisms BARNES (1959).

-J:''*||

"' ' ' ''' "' ' - 33 -

The benthos sampling methods were dealt with in a very extensive paper by HOLME (1964). In the eastern Mediterranean of the Israel coast the Petersen Bottom Grab, Dredge and Beam Trawl were used. The last two gears were specially constructed and their performance described GILAT (1963). Fishes are taken by means of commercial gears used in the Mediterranean.

A grid of stations was established in Haifa Bay for sampling water and organisms. The water samples were taken within monthly intervals at five stations from December 1966 to March 1967. The sonic depth of the stations varied between the depths of 10 to 150 fathoms. The sampling was planned so as to cover the depth layers of 0, 10, 20, 30, 50, 75, 100 and 200 metres.

The stations in which water was sampled were as follows :

Station Sonic depth Sampling depth No. (fathoms) (metres)

1 10 10 3 17 20 7 20 30 10 50 50,75 11 100 0,100,200

The sampling was carried out during day hours 0900 - 1600. Their volume was 20 litres in shallow waters. Larger samples of 40 - 80 litres were taken in deep water stations.

The work was carried out on board the research vessel R/V Mevo'ot Yam, (110 BRT) of the Department of Fisheries, Ministry of Agriculture. The research vessel is a steel cutter 21.85 m length, powered by a 150 HP engine.

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.

'> (5 ' '¿»Vi - 34 -

As the first radionuclide to be determined, Sr-90 was chosen. This nuclide is among the most hazardous of those produced in nuclear opera- tions, because it is concentrated in the bony tissue and it is of a relatively long biological half-life.

The area chosen at the early stages of this investigation foras a part of the continental shelf of Israel in the eastern Mediterranean. The water samples were taken in five stations in Haifa Bay at monthly intervals and at various depth levels. The organisms were collected on the sea bed in two main areas, at various depths.

An ecological study was conducted on the distribution of the benthic invertebrates which form an important link in the marine food chain.

Sediment samples were collected from stations in which biota were taken in order to determine their radionuclide content for comparison with radionuclide content in organisms living on the sea bed. During the hydrographie cruises water samples from sea surface were also taken in the Levant Basin in May and July 1967.

Previous studies on the physical-chemical and biological processes affecting the dispersion of radionuclides in the eastern Mediterranean were accomplished under IAEA Contract No. 1118/RB OREN et al. (1964). - 35 -

Saapling of surface waters was also performed during cruises of the R/V "Shikaona" belonging to the Océanographie and Lianological Research Co., the National Council for Research and Development, in a number of stations in the Levant Basin.*

The list of water samples is given in Tables 3.1, .3.2 andv3.3, and the grid of stations in which both water and organisas were saapled is plotted in Map I.

In the hydrographie laboratory of the Sea Fisheries Research Station the salinity and pH of the water sanples was determined and the values are included in the list of samples. lite salinity was measured in the C.S.I.R.O. Inductively Coupled Salinometer, which is used as standard equipment in the laboratory. The gear used for saapling of marine organisms was composed of two types of dredges which were effective for different characters of substratum and trawl nets.

The Petersen grab 0.2 m was only recently introduced as a sampling gear in this area with the purpose of calculating the standing crop of benthos per unit of sea bed.

*The cruises on board the R/V "Shikraona" were carried out with the objective of studying the hydrographie conditions of the Levant Basin. - ób -

Tablé 3.1

Sea Water Samples Collected in Haifa Bay, November 1966 - June 1967

Sample Sampling Station* Sampling Sonic No. Date Depth Depth Salinity pH (metres) (fathoms)

1 25.11.66 3 20 17 _ 2 5.12.66 7 30 20 - - 3 28.12.66 10 50 50 - - 4 11. 1.67 11 100 100 39.128 8.20 5 11. 1.67 11 0 100 39.100 8.20 6 11. 1.67 10 75 40 39.048 8.20 7 11. 1.67 10 50 40 39.104 8.20 8 11. 1.67 7 30 20 39.104 8.20 9 11. 1.67 3 20 17 39.052 8.00 10 11. 1.67 1 10 10 39.048 8.20 11 26. 1.67 1 10 10 39.068 8.15 12 26. 1.67 3 20 17 39.056 8.20 13 26. 1.67 7 30 20 39.056 8.20 14 26. 1.67 10 50 50 39.056 8.20 15 26. 1.67 10 75 50 39,060 8.20 16 26. 1.67 11 200 140 39.184 8.20 17 26. 1.67 11 100 140 39.056 8.20 18** 26. 1.67 11 0 140 39.032 8.20 19 7. 2.67 11 0 130 39.007 8.00 20 7. 2.67 11 100 130 39.014 8.00 21 7. 2.67 11 200 130 39.014 8.00 22 7. 2.67 10 75 50 39.027 7.90 23 7. 2.67 10 50 50 39.014 7.90 24 7. 2.67 7 30 20 39.006 8.00 25 7. 2.67 3 20 17 38.995 8.00 26 7. 2.67 1 10 10 38.914 8.00 27 26. 2.67 11 200 130 39.095 8.05 28 . 26. 2.67 11 100 ISO 38.918 8.15 29 26. 2.67 11 0 150 38.931 8.15

*See Map 1 in 1st Progress Report, IAEA, Decenber 1966 - August 1967, TNSD-142 **Volume of Sample No. 18 - 80 litres.

•'I*" "' \, -r . !.. - 37 - Table 3.1 (cont'd) Sea Water Samples Collected in Haifa Bay

Sample Sampling Station Sampling Sonic No. Date Depth Depth Salinity PH (metres) (fathoas)

30 13.3.67 11 200 140 39.053 8.15 31 13.3.67 11 0 140 38.980 8.05 32 13.3.67 11 100 140 39.008 8.10 33 13.3.67 10 75 50 39.008 8.10 34 13.3.67 10 50 50 38.979 8.08 35 13.3.67 7 30 20 38.980 8.05 36 13.3.67 3 20 17 - - 37 13.3.67 1 10 10 - - 38 31.3.67 11 200 130 - - 39 31.3.67 11 100 130 38.906 7.80 40 31.3.67 11 0 130 38.838 7.70 41 31.3.67 10 75 50 38.914 7.90 42 31.3.67 10 50 50 38.842 7.80 43 31.3.67 7 30 20 38.830 7.80 44 31.3.67 3 20 17 38.660 7.30 45 31.3.67 1 10 10 38.522 7.80 46 28.4.67 11 100 130 38.961 8.05 47 28.4.67 11 0 130 38.923 8.05 48 28.4.67 10 50 50 38.927 8.05 49 2.5.67 7 30 20 38.986 8.00 50 2.5.67 3 20 17 38.983 8.00 51 2.5.67 1 10 10 38.995 8.00 52 23.7.67 7 30 20 39.075 7.85 53 23.7.67 3 20 17 39.067 7.90 54 23.7.67 1 10 10 39.199 7.85 55 28.7.67 11 200 130 39.711 7.90 56 28v7.67 11 100 130 38.731 7.90 57 28.7.67 11 0 130 39.075 7.95 58 28.7.67 10 75 50 38.767 7.95 59 28.7.67 10 50 50 38.719 7.90 - 38 -

Table 3.2

Sanpling of Water off Sinai Peninsula* at the Surface

Sonic Sanpling Latitude Longitude Depth Salinity PH Date N E (fathoms)

12.7.67 31°22' 33o08« 4 38.921 7.95 13.7.67 Sl^l1 34°25' 5 39.191 7.90 13.7.67 31°34' 34°21' 20 38.912 7.90 14.7.67 31°21« 34°12» 5 39.224 7.90 14.7.67 31°24' 34°09' 20 39.056 8.05 14.7.67 31°31' 34°04' 75 38.882 8.00 14.7.67 31°33» 33°50' 150 38.897 8.00 14.7.67 31°27' 33°49' 45 38.803 7.95 14.7.67 3l'17« 31°17' 20 38.980 8.00 14.7.67 31°09' 31°09« 5 39.178 8.00

*See Map III

•"•>#'.."' m '••.-=. J • V.'- - - 39 -

Table 3.3

Sea Water Samples Collected at the Surface in the Eastern Mediterranean*

Sampling Station Depth pH Date (fathoms) Salinity

18.5.67 1 51 38.977 8.15 18.5.67 2 625 39.087 8.28 19.5.67 3 800 39.156 8.08 19.5.67 4 1200 38.620 8.22 20.5.67 5 1600 38.903 8.10 20.5.67 6 1400 39.036 8.21 21.5.67 7 1540 38.815 8.25 22.5.67 8 1200 38.624 8.28 22.5.67 9 1550 38.875 8.25 23.5.67 10 560 39.023 8.20 23.5.67 11 150 39.003 8.20 21.6.67 12 300-400 39.460 7.95 22.6.67 13 1000 39.380 8.15 24.6.67 14 300-400 39.267 — 24.6.67 15 1000 39.460 8.05 25.6.67 16 SOO 39.349 8.00 25.6.67 17 700 39.112 8.00 25,6.67 18 300-400 39.280 7.95 25.6.67 19 300 39.292 8.05 26.6.67 20 500 — — 26.6.67 21 800 39.035 7.95 28.6.67 22 300 39.276 7.95 28.6.67 23 1000. 39.360 7.95 29.6.67 24 600 39.373 7.95

*Cyprus Cruise 05 - May-June 1967. Map included in IAEA Report TNSD-R/401, Second Progress Report, September 1967 - February 1968. - 40 -

The subsurface water samples were taken at the stations established for this investigation in Haifa Bay and later at a station situated between the Israeli continental shelf and Cyprus, at a depth ranging from surface to 1,000 metres. The salinity and pH were determined for the sea water samples which will be processed in order to determine the contents of Sr-90 and Cs-137.

Temperature of the water layers at the time of sampling was measured using a bathythermograph and reversing thermometers. The list of water samples collected during 1968-69 is presented in Tables 3.4 and 3,5.

The sampling of surface water was extended to the eastern basin of the Mediterranean Sea, covering twenty four stations, the most.distant of them being placed at longitude 25°E. Most of the stations were concen- trated between the continental shelf of Israel and the coast of Turkey.

The organisms were sampled both for ecological studies and deter- minations of radioéléments 'in two areas: Haifa Bay and off Tantura.

A series of sediment samples were also taken on which granulometrie analysis was carried out in order to show the proportion of sand, silt and clay in various localities. The temperature and salinity data were also compiled and will serve for interpretation of environmental condi- tions in relation to the distribution of the organisms.

Since preliminary results were obtained on the Sr-90 content of the surface waters, the effort was directed toward determination of this radionuclide in deeper water layers and in some marine organisms. - 41 -

Table 3.4

Sea Water Samples Collected at Different Depths in the Mediterranean*

Sample Sampling Depth Temperature Salinity No. Date (metres) (centigrades) (per ai 11) pH

60 20.6.68 0 24.42 39.057 7.95 61 20.6.68 100 16.75 38.881 7.95 62 20.6.68 200 16.41 38.941 8.00 63 20.6.68 300 15.83 39.114 7.90 64 20.6.68 500 14.50 38.989 7.95

"Cruise to the eastern Mediterranean - Cyprus-09 Geographic position of the station - 33°10'N ; 33°50fE Sonic depth in fathoms - 1,750 Sample volume - 90 litres

Table 3.5

Sample Sampling Depth Salinity No. Date (metres) (per mill) pH

65 10.3.69 0 38.750 8.10 66 10.3.69 100 67 10.3.69 200 38.927 8.05 68 10.3.69 300 38.923 8.05 69 10.3.69 500 70 10.3.69 1000 38.736 8.02

'Cruise C-12 of Research Vessel "Shikmona" Geographicposition^of the station - 33°45IN ; 34°07«E Sonic depth in fathoms - 1,200 . Sample volume - 80 jjitres - 42 -

The sampling of sea water was carried out in the area between the Israeli continental shelf and Cyprus, November 1969 at the 'onic depth of 1,000 fathoms, geographical position - 34°10'N ; 33°28'E, during C-15 cruise of the R/V "Shikmona" (Table 3.6).

This is the third series of deep-water samples taken using the standard 30 litre plastic sampler as in the former cruises. The volume of water collected for determination of Sr-90 and Cs-137 was 40 litres for the range of depth between the surface and 1,000 netrès.

The data on temperatures at the sampling depth were not finally processed by NODC, but numbers are available for corrected depths which are as follows:

Depth Temperature (metres) °C*

1 23.15 117 16.67 231 15.37 308 14.85 472 14.24 1,120 13.65

*Data on temperature, salinity and pH were placed at our disposal by the hydrographie section of SFRS with permission of O.H. Oren. ,-/:,'•: ••[»•»[ •.•f" ,•'•*«-•!•;•,';" ''-•".* :„-&?' •^•'îîV- ;i¿&:- -íK

- 43 -

Table 3.6

Sea Water Samples Collected at Different Depths in the Eastern Mediterranean*

Sample Sampling Depth Salinity Sample Volume No. Date (metres) (per mill) pH (litres)

71 8.11.69 0 39.232 8.10 40 72 S.11.69 100 38.970 8.05 40 73 8.11.69 200 39.067 8.00 40 74 8.11.69 300 39.076 8.00 40 75 8.11.69 500 39.059 8.00 40 76 8.11.69 1000 38.788 7.98 20

»Cruise C-15 of Research Vessel "Shikmona" Geographic position of the station - 34°10'N ; 33°28'E Sonic depth in fathoms - 1,000

Invertebrate samples collected for determination of Sr-90 and Cs-137 during the years 1969-70 are composed of a variety of species, representing members of benthic communities - e.g. shrimps, crabs, molluscs and echinoderms (Table 3.8).

1 - 44 -

3.1.2 Biological Samples

A series of marine organisms taken in trawl at the continental shelf was ashed in 550°C, the list of which is presented in Table 3.4. These are the most common invertebrate species which appear in the commer- cial trawl catches of which the shrimps and squids are edible. The shrimps and crabs are migratory animals with relatively little vertical movement while the squids of'the genera Loligo and Sepia may be taken as indicators of transport of radiönuclides between the surface and sea bottom.

Other organisms, especially the Echinoderms, would indicate the uptake of radiönuclides from the sediments, since species such as Brissopsis lyrifera burrow into sediment and are detritus feeders.

Organisms collected in the past e.g., Squilla massavensis, an Indo- Pacific species, were also ashed with the purpose of comparing the Sr-90 content within an interval of eight years (1960-68) in the same geogra- phical area.

The list of species used for Sr-90 and Cs-137 content determination comprises the following taxonomic groups of invertebrates: Anthozoa, Decapoda, Stomatopoda, Cephalopoda, Echinodermata.

Most important in the list presented in Table 3.7, are the edible shrimps of the Penaeidae family, of which Arjsteomorpha foliácea, which lives at larger depths, extending deeper than 100 fathoms. One sample of this species collected in 1953 was chosen for comparison with recent data.

Two species of decapods: a shrimp, Parapenaeus longirostris of Atlantic Mediterranean distribution and a crab, Charybdis longicollis of Indo-Pacific origin, were taken since 1961 enabling the comparison of fallout nuclides content in their bodies within a period of one decade. - 45 -

The material of P. longirostris, collected off the island of Malta (July 1956, Sample 81) permits obtaining data on the radioactive contamination of the shrimp population in other areas to be compared with that of the same organism, in the eastern Mediterranean.

The range of depth of the collected material extends between 15 to 45 fathoms, covering the sediments of sand, silt and clay on the continental shelf.

The species: Pennatula rubra and Alcyonium palmatum coral like sedentary animals, being filter feeders, are indicators of the contamina- tion due to suspended particles of organic and inorganic character. - 46 -

Table 3.7

Invertebrate Samples Collected for Radioactivity Determination

Weight in gm Sample Species vttbData« oWfX No. Collection Wet Dry Ash 1 Parapenaeus longirostris 19.12.64 19.81 3.60 0.578 2 Parapenaeus longirostris — 38.54 8.76 1.276 3 Parapenaeus longirostris — 265.67 48.38 8.136 4 Parapenaeus longirostris 17. 8.65 286.70 56.67 9.232 5 Sepia officinalis — 56.80 12.46 0.862 5/2 Sepia officinalis — 157.10 27.46 1.423 5/3 Sepia officinalis — 17.50 6.36 5.376 6 Sepia officinalis 9.12.65 121.00 19.55 1.355 6/2 Sepia officinalis 9.12.65 6.50 4.36 3.862 6/3 Sepia officinalis 9.12.65 36.30 7.04 0.689 7 Schizaster canaliferus — 234.70 117.25 109.775 8 Pennatula rubra 17. 8.65 131.80 23.25 19.399 9 Squilla mantis 23.12.65 99.67 22.15 5.747 10 Charybdis longicollis 23.12.65 13.87 3.86 1.942 11 Pennatula rubra 23.12.65 51.00 10.85 6.305 12/1 Loligo vulgaris 22.12.65 183.60 52.61 2.244 12/2 Loligo vulgaris 22.12.65 142.40 52.13 2.463 13 Penaeus kerathurus 22.12.65 22.80 6.40 0.950 14 Penaeus semisulcatus 22.12.65 33.80 8.60 1.000 15 Sepia officinalis 4.10.66 4460.00 946.00 69.104 16 Loligo vulgaris -- 500.00 199.00 12.600 17 Parapenaeus longirostris 23.12.66 2400.00 543.00 101.300 Antedon mediterránea 7.12.66 350.00 134.60 98.450 19 Pennatula rubra 3.10,66 288.00 51.50 20 Pennatula rubra 25.11.66 334.00 66.60 ' 71.620 21 Astropecten aranciacus 25.11.66 477.60 210.20 126.400 22/A* Sepia officinalis 7.12.66 1340.00 309.60 23.200 22/B** Sepia officinalis 7.12.66 170.00 51.10 44.100

•Muscles of Sepia **Shell of Sepia

%\^?r,>?^\ ••' xi: s./ï r' - 47 -

Table 3.7 (cont'd) Invertebrate Samples Collected for Radioactivity Determination

Sample Species Date of Weifijit in gm. No. Collection Wet Dry Ash

23 Brissopsis lyrifera 9. 1.67 353730 128.90 120.300 24 Antedon mediterránea 9. 1.67 453.63 158.90 51.800 25 Fennatula rubra 10. 1.67 708.00 132.00 75.700 26 Parapenaeus longirostris 10. 1.67 237.00 36., 50 6.600 27 Antedon mediterránea 15. 3.67 141.60 61.30 " 41.300 28 Antedon mediterránea 6. 2.67 299.47 104.90 81.400 29 Loligo vulgaris 4. 5.67 940.00 222.60 42.600 30 Antedon mediterránea 10. 5.67 141.60 49.00 36.700 31 Parapenaeus longirostris 29. 4.67 309.20 65.40 9.000 32 Antedon mediterránea 15.'3.67 143.00 50.00 35.200 33 Pennatula rubra 27. 4.67 305.20 42.90 23.300 34 Pennatula rubra 27. 4.67 211.2 41.80 20.200 35 Antedon mediterránea 17. 5.67 315.00 106.30 78.200 36 Antedon mediterránea 18. 5.67 186.00 65.80 48.300 37 Brissopsis lyrifera 27. 4.67 413.80 119.00 104.900 38 Pennatula rubra 27. 4.67 238.60 43.80 22.800 39 Echinaster sepositus 27. 4.67 76.00 21.20 12.800 40 Echinaster sepositus 10. 1.67 21.00 7.70 5.100 41 Parapenaeus longirostris 3.10.67 134.80 26.40 5.100 42 Parapenaeus longirostris 1961-62 367.20 43.10 9.900 43 Parapenaeus longirostris 1961-62 256.10 50.50 8.300 44 Penaeus kerathutus 1961-62 322.40 74.90 10.300 45 Charybdis longicollis 1961-62 266.10 61.60 33.700 46 Charybdis longicollis 1961-62 287.6 80.20 42.700 47 Myra fugax 1961-62 348.50 147.80 98.500

48 %Penaeus semisulcatus 1961-62. 217.60 53.80 6.200 49 Brissopsis lyrifera 8. 9.67 300.00 91.10 ' 83.900 50 Brissopsis lyrifera 27. 8.65 165.00 58.50 53.200 51 Brissopsis lyrifera 6. 9.67 119,20 56.50 51.600

~ I ,.,\t ,{ - 48 -

Table 3.7 (cont'd)

Invertebrate Samples Collected for Radioactivity Determination

Sample Species Date of Weight in gm. No. Collection Wet Dry Ash 52 Charybdis longicollis 24.11,67 176.50 40.80 23.000 S3/A Sepia officinalis* 7.12.67 3162.20 754.10 84.700 53/B Sepia officinalis** 7.12.67 95.40 92.90 80.600 54 Astropecten aranciacus 6.11.67 279.80 104.10 72.400 55 Pennatula rubra 6.11.67 256.80 48.30 25.800 56 Antedon mediterránea 6.11.67 71.80 20.60 15.600 57 Sepia officinalis** 4. 3.68 975.00 207.70 " 14.700 58 Loligo vulgaris 4. 3.68 2602.00 658.40 37.300 59 Pennatula rubra 4. 3.68 371.50 79.10 33.300 60 Squilla mantis 4. 3.68 258.60 39.70 7.400 61 Brissopsis lyrifera 6. 5.68 1009.80 321.50 294.100 62 Astropecten aranciacus 6. 5.68 168.00 75.40 56.000 63 Pennatula rubra 6. 5.68 98.90 23.80 11.600 64 Squilla massavensis 22.12.60 577.40 73.30 17.700 65 Parapenaeus longirostris 4. 5.64 138.00 41.20 7.700 66 Loligo vulgaris*** 3. 4.68 366.40 88.10 12.500 67 Sepia officinalis* 3. 4.68 538.20 127.40 17.400 68 Cephalopoda 11. 7.68 862.00 176.20 17.400 69 Pennatula rubra 5. 8.68 285.00 48.60 23.200 70 Pennatula rubra 3. 4.69 1168.20 251.70 109.500 71 Parapenaeus longirostris 9. 5.69 1210.00 315.20 60.000 72 Sepia officinalis* 9. 5.69 1355.60 328.30 43.200 73 Pennatula rubra 9. 5.69 248.00 57.80 26.200

*Muscles of Sepia **Shell of Sepia ***Total body

1 h- - 49 -

Table 3.7 (cont'd)

Invertebrate Samples Collected for Radioactivity Determination

Sample Species Date of , Weifijht in gm. No. Collection Wet Dry Ash

74 Octopus vulgaris 30. 7.69 1049.40 160.10 8.800 75* Sepia officinalis 30. 7.69 522.40 94.50 7.400 76 Charybdis longicollis 2.11.61 375.10 93.20 49.900 77 Parapenaeus longirostris 2.11.61 397.80 79.00 11.100 78 Parapenaseu longirostris 18. 5.67 743.20 139.40 19.700 79 Pennatula rubra 18. 5.67 485.20 95.70 48.600 80 Aristeomorpha foliácea 1953 203.80 33.50 5.500 81 Parapenaeus longirostris 18. 7.56 163.00 34.80 5.700 82 Penaeus kerathurus 1.57 127.50 29.80 4.500 83 Penaeus semisulcatus -- 746.50 150.10 17.000 84 Squilla Massavensis 1966-67 140.00 28.80 — 85 Metapenaeus monoceros 1947 253.50 43.30 -- 86 Penaeus japonicus 9.12.69 2500.00 730.00 -- 87 Pennatula rubra 11. 7.68 754.70 162.80 — 88 Brissopsis lyrifera 17. 3.69 2050.00 560.00 89 Portunus hastatus 4. 2.70 550.00 151.40 — 90 Metapenaeus monoceros 4. 2.70 687.00 149.20 -- 91* Sepia officinalis 4. 2.70 6280.00 1230.00 — 92 Penaeus japonicus 4. 2.70 482.1 121.20 -- 93 Parapenaeus longirostris 4. 2.70 256.30 47.80 — 94 Squilla massavensis 4. 2.70 141.10 30.60 8.900 95 Loligo vulgaris 4. 2.70 338.20 57.10 — 96 Brissopsis lyrifera 6. 1.70 618.50 153.30 — 97 Alcyonium palmatum 6. 1.70 64.50 10.00 6.600 98 Upogebia tipica 8.12.69 3.50 0.60 — 99 Charybdis longicollis 10.11.69 2860.60 845.80 — 100 Astropecten aranciacus 15. 6.70 270.00 122.70 -- 101 Parapenaeus longirostris 15. 6.70 103.60 25.00 —

•Muscles - 50 -

Table 3.8

Biological Samples for v-Spectrometry

Sample Date of Weight in gm. Depth Species Locality No. Collection Wet Dry (fms.)

102 Charybdis longicollis 15. 6.70 607.10 120.20 Haifa Bay 20-40 103 Astropecten aranciacus 15. 6.70 116.60 44.80 Haifa Bay 20-40 104 Brissopsis lyrifera 5. 1.70 1641.20 473.80 Ashdod 30 105 Pennatula rubra 20. 4.71 708.00 154.20 (Invertebrate)

106 Siganus luridus 29.10.70 Haifa Bay 5 \ (fish)

107 Sardinella aurita 17. 5.70 Herzlia 19 (small fish)

108 Mugil spp. 12. 5.71 Bardawil M. cephalus & M. capito Lagoon (headless)

109 Sardina pilchardus 17. 5.71 • Netanya 24 110 Sardinella aurita 17. S.71 1574.00 Netanya 24

^ - 51 -

90 3.2 Determination of Sr in Sea Water and Biota

3.2.1 Radiochemical Separation Procedures

Sea Water - General

Samples of sea water of usual volume of 20-25 litres were collected and transferred to a polyethylene container to minimize problems of contamination and adsorption. The water sample was acidified to pH2 by adding concentrated hydrochloric acid immediately after collection on board the research vessel.

The "liquid phase" of the sea water was defined by filtering the water sample through a millipore filter 0.45u mean pore size and made of pure cellulose esters (Type HAWP 142 Millipore Filter Corporation). The filtration was performed using a PVC filtering transfer pump. In this way, all the particulate matter and organisms of about 0.45y diameter or more were retained on the millipore filter.

90Sr from Sea Water

A radiochemical method for the isolation of strontium-90 from the above defined "liquid phase" of the sea water was worked out. The method applied is based on similar work by SUGIHARA et al.(1959) with minor modifications,,

All the reagents used are of analytical reagent grade.

The strontium separation involves an initial direct precipitation of mixed strontium and calcium carbonates. In order to eliminate the • bulk of the calcium, carbonate precipitation is then carried out twice in the presence of versene (ethylene dinitrilotetra-acetate ion - EDTA). Further separation from calcium is effected by precipitation of nitrates. Scavenging with ferric hydroxide - barium chromate and final conversion to strontium, carbonate complete the extraction process.

T '•• V

- 52 -

The filtrate of the initial mixed carbonate precipitate is preserved for subsequent cesium separation, after acidification with nitric acid to pH 1-2 inhibit the growth of organic organisms.

In the precipitation of carbonates in the presence of versene, the calcium-EDTA stability constant is about 100 times greater than that of strontium-EDTA. The presence of EDTA reduces the amount of calcium carbonate precipitate formed, but the strontium is hardly affected as long as the number of moles of EDTA present is somewhat less than that of calcium. The amount of versene used was thus made to be somewhat less than that of the estimated amount of calcium present in both instances.

The strontium content in the separated strontium obtained is deter- mined by counting measurements. The relatively high strontium concentration in sea water, which is about 8.2 mg/£ at chlorinity 19.39 per mill, BOWEN and SUGIHARA (1957), makes it very difficult to count strontium-90 directly, because of its low specific activity and high self absorption. It is thus advantageous to count the ß-disintegration product, yttrium-90, whose half life is 64.5 hours and which can be separated with a higher specific activity. Y-90 has a maximum ß-energy of 2.27 MeV and self absorption problems are therefore minimized.

The strontium carbonate precipitate is put aside for ?*• least 15 days to allow the Y-90 to grow into secular equilibrium with its parent Sr-90 activity. The milking of the Y-90 activity is then performed by first dissolving the Sr-Y carbonate in hydrocholoric acid, then separating the Y-90 fraction by co-adsorption on ferric hydroxide. This precipitate is filtered off by suction on to a one inch diameter HA millipore filter. After drying at 110°C, the sample is mounted and covered with parafilm.

Originally the sample was mounted on a stainless steel planchet, but this was later replaced by a nylon planchet with a ring in order to reduce the background of the low level beta counting system. This background is determined before and after each sample count and is on average about 0.21 cpm • A further advantage of the with-ring-type nylon planchet was the improvement of the counting geometry and consequently the counting statistics. - 53 -

The chemical separation yield of strontium (n_ ) is defined as the or ratio of the weight of strontium ion obtained after the separation and the sum of the weight of strontium ion added as carrier and stable strontium present naturally in the sea water sample. The stable strontium content is readily calculated making use of the constant strontium - chlorinity ratio in sea water ODUM.(1951)and CHOW $ THOMPSON (1955). The chlorinity for each sample was obtained from the measured salinity using the Knudsen equation [STRICKLAND $ PARSONS (1965).

In order to be satisfied that no exterior radioactive contamination entered during the entire process, a blank sample of. 10 litres of conduc- tivity water has been processed using thé same reagents in the same relative amounts as used in a 20 litre sea water sample. The activity obtained was negligible.

90 Sr Separations from Biota

The marine organisms were first treated in the usual way — i.e. first Washed in fresh water, then dried at 110°C to constant weight and ashed for 16-24 hours at 550°C, The fresh weight, the dry weight, and the ash weight were noted.

To facilitate chemical extraction, the sample was preferred in powder form. A vertical vibration ball mill was used to crush the sample. The whole quantity of available ashed sample, was crushed to a fine powder and thoroughly mixed, and only then was the amount to be analysed removed. This procedure ensured a greater degree of homogeneity for the sample, besides saving hours of futile labor.

For chemical extractions, 50g. of crushed, ashed biota are weighed out and treated w*th aqua regia followed'by HP on any remaining solid.

The radiochemical separation method used is that developed by MIYAKE, et al. (1964) with a modification of the nitration procedure to that presented by SUGIHARA, et al.(19S9). Initial precipitation of mixed strontium-calciu»- barium carbonates is effected from the solution resulting fro» th» aqua regia and HF treatments. < - 54 -

Strontium is then isolated by repeated precipitation of strontium nitrate in 76% nitric acid. The rare earths and trivalent cations are removed by ferric hydroxide scavenging, and radium and lead are removed by co-precipitation with barium enrómate. The strontium is finally obtained as the carbonate and is stored for Y-90 ingrowth. The milking and counting procedure is exactly as described for Sr-90 in sea water.

All reagents used were of analytical grade and have been checked for radioactive contamination which was found to be negligible.

3.2.2 Low Level Beta Counting

The beta counting equipment used in Sr-90 determinations combines the qualities most important in low level counting. As mentioned, due to self-absorption, chemical separation must be performed on every sample before counting, and the samples must be prepared as uniform thin discs. The Omni/Guard Low Background Beta Counting System used is a 2* geometry gas flow system equipped with anticoincidence and external shielding.

The detection unit consists of a dome guard counter having a single-loop anode. The cavity of the guard counter contains a relatively flat sample counter of 1 1/4" window diameter and ~100 ug/cm2 thickness that also has a single-wire anode. Both counters are arranged such that radiation from the sample will only trigger the inner counter, while cosmic rays must pass through and trigger the guard counter before reaching the inner counter. The output of the two detectors is fed into an anticoincidence circuit which rejects all pulses from the inner counter that are accompanied by a simultaneous pulse from the guard counter as determined by the resolving time of the system. Cosmic and terrestrial radiation is reduced by four inches of lead on all sides. The planchet diameter is 1 inch and the space between the counter window and the sample surface is 1 mm.

Tracerlab, U.S.A. - 55 -

Figure (3.1) is a block diagram of the low level beta counting system. A small air-conditioned underground room with 2 foot thick stone walls and a constant temperature of about 22°C serves as the counting room. The room is equipped with a filtered air inlet and special precautions are taken to keep the room clean from dust and thus maintain a minimum back- ground level.

3.2.3 Measurement Analysis

The absolute Sr-90 activity in pjic/unit of sample is determined by an analytical procedure following the measurement of the ingrown Y-90. The measurement is taken over an extended period of time to ensure statistical accuracy as the half-life of Y-90 is of the same order of magnitude as the necessary counting time. A graphical representation of the Y-90 ingrowth in the separated Sr-90.sample and.its.decay after separation from Sr-90.is shown in fig; (3.2). The absolute Sr-90 activity which can be designated to a certain counting sample of Y-90 will thus be given by the following equation:

-90)]/ [uyc/unit] [3.1] unit -X(t2-ti) 133.2 nSr A[e - e

where:

N„ „ Total number of counts from sample and background counted from

t2 to t^ (counts). Background count rate (cpm). Decay constant for Y-90 decay (hours'' )). Time of precipitation of strontium carbonate (reference time). Time of separation of Y-90 from Sr-90 * Y-90 ingrowth time (hours).

Start time of Y-9Uutteuhtiíi¿. - : t. •",.,' End of integral counting of Y-90 (hours). - 56 -

Number of units in sample, i.e. volume of sea water sample (litres) of ash weight of marine biota sample (grams). Chemical separation yield of strontium "Sr Reciprocal counter efficiency for counting Y-90 as co-precipitated on 2 3.1 mg/cm Fe(OH)3, using the mounting and geometry described before (dps/cps).

Accuracy of Sr-90 Determination and Optimization of Counting Times

The accuracy of the final result of the determination of the content of Sr-90 in sea water and biota depends in the first place on the standard deviation of the Y-90 measurement. The standard deviation for the net count rate of Y-90 can easily be derived frcm the total number of sample plus background counts obtained during a certain counting period, taking into consideration the radioactive decay of Y-90 during this period, and the standard deviation of the background determination. Equation [3.2] gives the standard deviation for the net count rate of Y-90 at the time of its separation from Sr-90:

1/2 - e VW

[cpm] . [3.2] - e where the symbols are as explained for equation [3.1] .and:

Ag - The net sample count rate of Y-90 at the time of its separation from Sr-90 (cpm) „ • tg - Duration of background measurement (hours).

In order to find the optimum tines for sample plus background (t3-t2) and background (tB), graphic representations of o|l as a function of tß, according to equation [3.2] were used. For a number of different net sample count rates * As , groups of curves were obtained with various (t3~t2) values as parameter. - 57 -

In fig. (3.3) a group of curves for A. = 0.6 cpm is represented. It can easily be seen that for background counting periods tg larger than about 40 hours, the slope of the curves becomes moderate. Therefore, the use of larger tg values will yield only relatively small improvements for 0*1. For tg * 40 hours the optimum sample plus background counting time lies around (t3-t2) * 80 hours, but only little less favorable og values may be obtained with (tj^) values around 60 hours.

In conclusion, under the experimental conditions described, for a total counting time [tB + (t3-t2)] of about 100-120 hours, [tB] * 40 hours and (t3-t2) t< 60 - 80 hours], a standard deviation being higher only by about 20% than the minimum possible standard deviation, can be achieved.

Expressing the accuracy of the Sr-90 content of the investigated sample as a standard deviation; this will be given by:

1/2 to [wc/unit] [3.3]

where:

Standard deviation of the absolute counter calibration.

Standard deviation of the chemical separation yield of Sr-90 "Sr - 58 -

Verification of Pure Y-90 Separation

The complete selctivity of the Y-90 separation from the strontium carbonate precipitate was verified by least squares analysis of the counting results of the final sample.

Several samples were counted over a period of more than three half- lives -- namely over 200 hours -- and the counting results recorded every two hours.

Least squares analysis of the net results, after substraction of the background, yielded a hlaf-life 66 ± 1 hours. This figure differs only by 2.3% from the accepted half-life value of Y-90 which is 64.5 hours.

Background and Counter Stability Measurements

A background and a standard source measurement was made between each sample counting. In this way a certain number of similar measurements were performed over a long period of time. In order to check proper counter operation and to verify the statistical reproducibility of the measurements, control chart and statistical testing techniques were used.

The results of the background measurements performed were inserted into a control chart and showed statistical reproducibility around a mean value of 0.212 cpm with a standard deviation of 0.034 cpm. In the same way the standard source measurements were checked on a control chart. The results proved excellent counter stability within the statistical limits of the measurements which were ±0.3%. Figure (3.4) is a sample background control chart.

In order to test the counter reliability over long periods of time the Chi-square statistical test was performed with a high activity standard source at regular intervals. This test indicates syste» defects that are liable to go undetected otherwise, and may introduce non-random factors into the counting. Intermittent failure to count pulses fro« loose connections, electronic component failures, or spurious pulses fro» insulation breakdown can result in such non-random accumulations. "Ü..-

- 59 -

3.3 Low Level Ge(Li) Gamma Spectrometer

3.3.1 Application of Solid-state Detectors to Low-level Gamma Detection

A common problem in radiochemical arid radiobiological studies is the identification and measurement of several components in a complex radionuclide emit one or more gamma photons during the course of their decay, gamma detection can be a powerful tool in such studies.

The properties demanded of an extremely low-level counting system are lowest possible background, high efficiency, and sharp resolution. Until quite receltly the Nal(TA) scintillator was the mainstay of all gamma spectrometers. However its poor resolution often made necessary tedious and expensive chemical separation of the isotopes sought. These procedures often introduce serious uncertainly in the chemical yield. Although multidimensional spectrometry in conjunction with NaI(T&) permits a more detailed analysis of complex samples, it enjoys only limited use due to high cost and its suitability to cascading decay schemes.

The requirements stated above and the limited success in fulfilling them have prompted the introduction of the new generation of large- volume solid-state detectors to low-level spectrometery. Their success has been clearly established in the literature COOPER,(1968,70) PHELPS (1968). Ge(Li) detectors now constitute the basis for systems providing direct analysis of complex radionuclide mixtures. Chemical preparation of the samples is minimal, confidence in the results is higher, and unambiguous identification of radionuclides is ensured.

The system described herein was designed and built primarily for use in marine environment studies on radionuclides present in the eastern Mediterranean Sea. Specifically sought were the concentrations of radio- nuclides resulting from radioactive fallout in sea water, biota, and sediments.

The optimization of the system must b« considered a practical optimization rather than a maximum performance optimization. Due to the financial expenditure necessary for what was determined tc be such a

m - 60 - maximum performance system, the capabilities of this system had to be limited more closely to the problem at hand. Preliminary results of the performance have been presented a year ago ,LEWIS et al.(1970). A more detailed description was published recently LEWIS and SHAFRIR (1971).

3.3.2 Spectrometer Design

A detailed study of existing Ge(Li) anticoincidence systems PHELPS et al., (1968), COOPER et al., (1970), COOPER and BROWNELL.(1967), MICHAELIS and KUPFER (1967), CAMP (1967), COOPER et al., (1968), COOPER et al., (1968), related to the use of Ge(Li) as a main detector KAYE et al., (1968), STENBERG. and OESSON (1968), WOGMAN et al., (1969), PARKER et al., (1968), AUBLE et al., (1967), KANTELE and SNOMINEN (1966), EULER et al., (1969), NIELSON and KRONBERG (1965), revealed that numerous possibilities existed for the design of an optimum low level spectrometer.

The optimization was approached from several main directions:

a. Choice of a main detector based on resolution, efficiency and cost. b. Choice of the best material and geometry for the anticoincidence mantle based on efficiency, size and cost. c. Construction of the bulk cosmic ray shielding as regarded available space and materials, effectiveness and cost. d. Assembly of an electronic system to fulfill the requirements of flexibility, low noise, good linearity and stability, and sufficient MCA storage. 1

- 61 -

Detection efficiency was the deciding parameter in choosing a detector. The resolution attained by most large volume detectors is consistently good. Five-sided trapezoidal detectors are presently 3 available up to 120 cm volume.

At the time of the system's designing the largest available 3 3 detectors were of 60 cm volume. A detector of 42 cm volume was chosen as a satisfactory compromise between high efficiency and higher cost. The detector provides an efficiency of 5.6 per cent at 1.33 MeV relative to Nal (Tí,). The resolution at the same energy is 3.1 keV fwhm with a peak to Compton edge ratio of 18.5:1.

The detector is housed in a vacuum chamber mounted horizontally on a 31 liter liquid nitrogen dewar. To accommodate passage through lead shielding and into the mantle, the cap was made 12" long. Its diameter is 2.5". The configuration of the dewar was dictated by experimental conditions. In order to reduce the weekly expenditure of liquid nitrogen and prevent disturbance of long-term measurements, the dewar with longest holding time, the dip-stick variety consisting of a cooling rod extending vertically down into the dewar, was chosen. This configuration is also more stable against vibrations leading to microphonic noise, a specifically serious problem with such a long cold finger supporting the detector.

A cooled molecular sieve within the cryostat in conjunction with an external 0.5 liter/see ion pump serve to maintain and monitor a high vacuum (10 -4 torrj.

The Ge(Li) detector itself is located on the end of an OFHC copper cold finger at 13 mm from the 0.020" thick type 1100 aluminium endcap. The surface area of the crystal is 9.4 cm and it is 45 mm long. The n-layer thickness as revealed by copper staining is 0.4 mm. The drift depth is a minimum 12 mm.

1 -:. s ' - 62 -

Several preconditions were placed on the design of the mantle regardless of which scintillator material would be chosen:

a. Space limitations required a vertical orientation of the scintillator- photomultiplier assembly. b. An entrance port must be on the lateral surface to accommodate the Ge(Li) chamber. c. At least 200 cm sample space must be available, dt No sources of background radiation can be present. e. The mantle must provide effective coverage of all scattering angles for bulk samples. f. The cost must not be prohibitive for the dimensions that would ensure sufficient absorption.

Although plastic phosphors have poorer gamma absorption qualities than Nal (Tí,) thus requiring larger sizes, they have been used very effectively. The far lower cost of the material outweighs the increased cosmic ray shielding reqrired. The substance can be readily machined to any specifications. Encapsulation against the environment is unnecessary. The substances are insensitive to thermal shock. Hence, all scattering angles can be more effectively covered and no material is needed between the Ge(Li) housing and the plastic which would degrade the Compton suppression.

Although NE102A plastic is the most widely used, a newer, more transparent plastic, NE110, chosen for this project, has much better properties for large volumes. Its light attenuation length is 250 cm, giving it the best available light transmission. As finally designed, the plastic phosphor assembly cost one- half what an equivalent Nal(TA) assembly would have cost. The range of sizes of plastic mantles used in Compton suppression systems is very wide, the largest measuring 75 cm x 75 cm. Clearly, some basis for choosing optimum dimensions was required.

Evaluation of gamma absorption efficiency in plastic phosphors can be accomplished by considering the Compton absorption process. For detection a certain minimum energy transfer must take place. - 63 -

In a practical system this is effectively governed by the discriminator bias setting fixed above the noise level in the phosphor output channel. The cross section for sose given minimum transfer is then found by integrating the differential Compton cross section from the correspond- ing scattering angle to 180°. This integration has been performed for various bias levels by ROULSTON and NAQUI (1957)

A bias level above noise of 25 keV is generally attainable and was assumed for these calculations. Normal plastic phosphor has an electron density of 0.34 x 10 e"/cm . Several curves of efficiency Vs. phosphor thickness as a function of energy were prepared. A phosphor geometry was assumed that would be suitable to bulk sample counting: a right cylinder with the principal detector at the center. Thus the phosphor volume increased as x » X being the thickness required for a given efficiency. The curves in fig. 3.5 demonstrate the rapid increase in phosphor volume necessary to gain the final 10 - 20 per cent of efficiency. The slope is very gradual up to the 80 - 90 per cent region. A tremendous volume is needed to ensure total absorption, as borne out by the large phosphors of COOPER, et al., (1968). V.

As the vast majority of gammas have energies lower than 1000 keV SLATER (1962) it was decided to fix the phosphor dimensions to ensure 80 - 90 per cent efficiency for photons up to 1000 keV. This would result in a Compton reduction under ideal conditions of x5 and a very significant reduction in background.

.".£* The phosphor has a diameter of 40 cm and is 40 cm long. A lateral "" ' 3 well accommodates the Ge(Li) endcap as well as over 200 cm samples. Four 5" photomultipliers view the phosphor: two above and two below shifted 90°. They are EMI type 953OQs, chosen for their very low dark current and fitted with quartz faces to eliminate K. All are housed in anti-magnetic mu-metal. • s «*' The phosphor is vertically mounted on a stainless steel table with roller bearings to facilitate sample insertion. Thus no additional openings axe required, preserving a good coverage of scattering angles. - 64 -

The phosphor is coated with white reflector paint and house in stainless steel. No metal is between the phosphor and the vacuum chamber. A schematic diagram of the electronics used for the low level anticoinci- dence mode is shown in fig. (3.6).

The noise contribution from the Canberra 1408c preamplifier is 0.8 keV fwhm + 0.024 keV/pf capacitance. For thé 42 cm3 detector the noise output is then 1.6 keV fwhm, the ideal puiser resolution to be expected. The preamplifier has integral nonlinearity <0.1 per cent and gain stability <0.005 per cent/°C.

i The Ortec 410 amplifier is well suited to Ge(Li) operation. Output is available both in unipolar and bipolar for« for spectrum storage and timing. RC shaping can be varied widely. Equivalent noise at the unipolar output is less than 7uVrms. at maximum gain. Gain shift is <0.015 per cent/°C. Nonlinearity is <0.1 percent from 200 mV to v 10V. The Ortec 408 biased amplifier used here provides biasing of up to 90 per cent full range and gain x20. Gain shift is <0.01 per cent/°C times the gain factor. As low pulses from the biased aaplifier are liable not to fulfill the risetime requirement of the analyzer« a pulse stretcher must be included. The Ortec 411 Pulse Stretcher provides a minimum pulse width between 0.7 ysec and 3 usec. High voltage bias to the Ge(Li) is supplied by a unit designed by R. WITHNELL (1968)to solve a major problem of sudden power failures. Many detectors and their FET's are susceptible to damage by large voltage transients. This supply includes N. - C^ batteries which are kept charged to provide 7 hours of emergency operation with no transients whatsoever. Total ripple and noise is 1 mV and long term . drift is <0.6.per cent.

Of prime consideration in choosing the scintillation preaaplifiers was the lowest noise level to ensure detection of small pulses fro« the phosphor. 'As pulses are used only for gating, linearity is not, important. The Canberra 80S preamplifiers yield a noise level 50uV ras with a main amplifier gain of 500; Stability is <0.02 per cent/°C. - 65 -

The summing amplifier is a wideband linear amplifier providing linear summation of the four preamplifier output signals.

The scintillation amplifier need only provide a low noise level and high gain. The Elseint CAV-N-4 provides Gaussian shaping for the best signal-to-noise ratio, a noise contribution of SuV, and gain up to x600.

The integral discriminator provides logic pulses to operate the anticoincidence gate; The integral discriminator section of the Elseint LG-N-5 linear gate is here used by itself.

High voltage is supplied to the photomultipliers by a Hauner N-413B Power Supply designed for this purpose. The N-413B provides load regulation with 0.005 per cent change from 0 to 10 nm at 5000 volts. Noise and ripple are SO mV p.p. A Hanner NV-21 High Voltage Divider is provided to give individual control of the bias on each photomultiplier as even tubes of the same type cannot be expected to provide identical multiplication.

The multichannel analyzer is the Hewlett Packard 5410A with a 1024 channel memory. The logic pulse is taken fron the integral discriminator in the scintillator channel. With the time-to-peak setting at 2 usec, which equals the coincidence gate width, the resolving time for the system is effectively 2 ysec. fhis arrangement prevents the problem of matching instrument delay tiaes to ensure simultaneous arrival of the signal and the logic pulse at the analyzer.

The design of the bulk shielding and the physical layout of the system was limited by several considerations. Financial outlay had to be of prime concern. The décision was taken to build only a basic cosmic ray shield. Additional shielding measures such as borated paraffin blocks and x-ray absorption linings were to be included after consideration of initial results.

Lead was chosen as. the shielding material as it presents the greatest mass in the smallest area. The Ge(Li) vacuum chamber would have to pass the least thickness, and laboratory space would be fully

%t - 66 - utilized. A 10 cm' thickness was considered optimum as an increase to 15 cm yields only a 10 per cent reduction in background

Figures (S.7)and (3.8) show the dimensional layout of the system. It is situated in a small basement level room with 75 cm thick stone walls. One wall, facing the internal stone wall is sealed off and not lined, with lead« The stone presents mass shielding, .equivalent to 10 cm lead. The door weighs 750 kg and rolls easily on ball-bearing wheels to give a 40 cm opening for sample insertion and maintenance. The only other penetration is a 7 cm diameter hole fox., the Ge(Li) vacuum chamber.

The entire shield and the liquid nitrogen dewar rest on a 25 cm deep cement base necessary for structural support on the sand floor. Additionally, the base helps absorb ground-transmitted vibrations which add to the microphonic noise. The base is separated a few centimeters from the walls of the room to prevent transferrai of vibration by this path. A layer of 5 cm lead bricks covers the base inside the shield.

As further measures against microphonics the liquid nitrogen dewar is mounted on foam insulating pads on a 75 kg iron base which in turn is supported by three threaded posts. The three supports rest on hard rubber insulating pads. Several lead bricks are added to the mass of the iron base to further absorb ground vibrations. Construction of a steel-walled, sand-filled enclosure around the Ge(Li) assembly to absorb airborne vibrations is considered. - 67 -

3.3.3 Spectrometer Characteristics

The desired performance of the system in Compton suppression is anticipated by the use of photomultipliers as' shown in fig. (3.7). Because of damage to one of the tubes, the results given here are obtained with the function of only three tubes. Hence slightly improved Compton suppression can be expected when complete coverage of all areas of the plastic phosphor is ensured by the fourth photomultiplier.

The peak to Compton edge ratio for Cs is improved up to a factor x5 by the anticoincidence operation. Full energy peak reduction is however, significant at the yCi level due to chance coincidences resulting from the high phosphor efficiency and the long coincidence resolving time.

At extremely low levels such as those encountered in environmental measurements as the pCi level, the full energy peak is not affected by chance coincidence if the bias level exceeds signal noise. Hence the peak-to-Compton ratio extrapolated to nil peak reduction is listed as well. The reduction factors achieved agree well with the expected scintillator'efficiency prediction.

Figure (3.9) is a -Cs spectrum in the normal counting mode and in the anticoincidence counting mode.. In this case the Compton edge has been reduced by a factor of 3.5.

: The backscattering peak has been reduced by 4.5 and is altogether absent. The entire Compton distribution is perfectly flat down to x-ray energies and exhibits much less statistical fluctuation.

The gamma background consists primarily, of characteristic peaks from the natural radioactive nuclide chains situated on a smooth continuum comprised of cosmic ray-produced gammas and scattered and partially absorbed radiation. - 68 -

The extent of background reduction afforded by successive shielding arrangements is shown in fig. (3.10) over an energy up to 1000 keV and in fig. (3.11) with a reduced scale and up to 500 keV. Spectrum A, within the lead shielding, is qualitatively more complex. Strong peaks due to excitation of the characteristic lead x-rays emitted by the shield are prominent. The 49 keV gamma of U and the 91 keV gamma of Th from the uranium series appear. A strong peak at 185 keV results 235 from U in the actinium series. Two peaks at 238 keV and 242 keV can be discerned as belonging to Pb and Pb respectively. The Pb and Bi peaks predominate. The annihilation peak is drastically reduced due to interception of the cosmic air shower. Smaller peaks resulting from Ac in the thorium series and Rn in the actinium series also appear.

Table 3.i> lists the continuum background levels at several energies. The continuum is reduced by the lead shielding by an average factor of x20 reaching a factor x28 at low energies.

Table 3.9

Continuum background levels for various shielding arrangements

Continuum Energy No Shielding 10 cm. Lead Plastic Bulk Anticoinc. Mode (keV) (cpm/keV) (cpm/keV) (cpm/keV) (cpm/keV)

100 63.5 2.27 1.76 0.29 200 22.1 1.05 0.55 0.13 300 7.8 0.47 0.21 0.046 400 4.7 0.24 0.12 0.027 500 3.1 0.15 0.075 0.020 600 2.1 0.12 0.059 0.015 700 1.6 0.073 0,043 0.010 800 1.3 0.062 0.032 0.0075 900 .78 0.056 0.025 0.005 1000 .62 0.044 .0.018 0.0046 - 69 -

But now a large, complex peak appears between 150-175 keV comprising a large number of gammas too close in energy to be resolved. Before the anticoincidence mode was put into operation, this complex peak was covered by the slope of the continuum. The multiplet includes photons from several natural decay chain nuclides: Ra, Bi, nPh, Ac, and 212Pb. A small amount of 235,U at 185 keV still passes through or is contamination.

The three significant peaks of 214Pb and the peak of 214Bi at 609 keV are unaffected by the anticoincidence operation. This indicates that this remaining quantity consists of contamination in the detector, its housing and support, and the passage of external radiation through the unshielded vacuum chamber of the detector.

The annihilation peak is, as expected, almost completely removed by the anticoincidence operation, being reduced by a factor xl5. Clearly, if the pair production process occurs in the detector following absorption of a high energy gamma and one quantum is absorbed in the phosphor, the pair is eliminated from the Ge(Li) spectrum.

The continuum is reduced by a further average factor x4.5. The statistical fluctuation of the continuum is reduced in a like manner. Prom approximately 300 keV upwards the background is level and almost insignificant. Starting at about 500 keV the background level does not even affect the system's sensitivity at a statistical accuracy of 10 per cent.

214 In order to examine the source of the predominant peaks of Pb *51 A and Bi an experiment was run in which the 650 liters of normal air in the shield were replaced by aged nitrogen gas. Enough plastic bags were filled with nitrogen to completely fill the shield volume and expel the air. Consequent measurements showed the peaks of Pb and Bi to have been reduced by 25 per cent when the Ge(Li) detector was exposed. As the plastic phosphor is quite efficient in shielding the main detector, flushing with inert gas as required by other types of system is unnecessary. - 70 -

Absolute neasurements of the full energy peak efficiency as a function of energy for the fixed geometries decided upon were perfoi by preparing calibration standards from isotopes of known activity. As varying amounts of sample substance are available, ranging from SO grams to 500 grains, several standard calibration sources were prepared with like diameter and varying depth. As the counting geometry has horizontal alignment and only one size of sample container was available, liquid-base sources in special containers would be suitable.

Perspex containers were designed and built according to the exact dimensions of several sample containers up to maximum volume. The containers had thick perspex covers with 0-ring seals and a small hole for final filling of a liquid solution by syringe. Thus a liquid-base source could be prepared and perfect diffusion of the isotopes could be ensured by adding the proper carrier.

A solution of NaNO3 was prepared with specific gravity of 1.26. The average biota sample density is 1/22 and sea Water salts sample density is 1.30. So a small correction could be applied for the difference if needed. Calibrated solutions of Cs and Co were prepared and used. It was seen that there is no difference in the geometry factor as a function of energy, so the efficiency results could be confidently extrapolated to lower energies.

Containers were built in 1/4, 1/2, 3/4, and 1 times the maximum available volume. Absolute activities of the solutions ranged from 1.7 to 12 for the largest volume. CsG* and CoC*-.~ were added to the 137 60 Cs and Co solutions respectively to act as carriers. The containers were sealed with chloroform and a chloroform-perspex cement and heat- sealed into double plastic bags for final security. The results of absolute activity measurements are shown in fig. (3.12). They demonstrate the almost perfect homogeneity of the sources. Comparing these results with the curve of intrinsic efficiency vs. energy confirm that the geometry factor is independent of gamma energy and the absolute efficiency curves experimentally determined could be extrapolated to lower energy. - 71 -

Uncertainty in the absolute efficiency includes a possible 1 per cent error in extraction of the assumed activity of the calibrated solution and 1-2 per cent uncertainty in the actual value of the calibrated activity.

Figure (3.IS) is a cross-plot of the efficiency versus geometry data as a function of energy extrapolated between 2C0 keV and 1500 keV where the intrinsic efficiency curve is linear on a log-log plot.

The minimum detectable levels of activity that can be reached with an assumed statistical accuracy were calculated following an approach outlined by COOPER et al.(1970) as shown in equation [3.4] and using experimentally determined parameters,

pCi [3.4] where - minimum detectable activity at energy E

A - reciprocal of the fractional error

e(B) - absolute full energy peak efficiency at energy E

f - branching factor

t - counting time (minutes)

b - factor relating resolution fwhm to the number of channels in the peak

R(E) - resolution at energy E

- average background counts per channel

Calculations were performed for four different geometrical arrange- ments according to sample size in order to compare the effect of reduced - 72 - efficiency. One group of such calculations was executed for typical biota sancles assuming a counting time of 2000 ninutes and a statistical accuracy of 10 per cent, generally attainable fron such samples. The results of minimum detectable total activity calculations are presented in fig. (3.14) as a function of garana energy. The range of 200 keV to 1500 keV is limited by the confidence of absolute efficiency measurements to this range. Clearly the lowest total activity level is afforded by the smallest sample geometry, which yields the highest absolute efficiency. For example, the minimum total activity of Cs with a branching factor f = 0.85 for a 75 gram sample is 4.7 pCi.

Figure (3.15) shows the minimum detectable specific activity level for the same parameters as used in fig. (3.13). It is clearly seen that the availability of a large amount of sample material is advantageous. The larger geometries, although suffering lower absolute efficiency, allow a far lower specific activity limit. Up to an energy of about 900 keV however there is no advantage gained by using a sample much larger than one standard container (115 cm ) or an average mass of 150 grams. Beyond this point the lower geometrical advantage of the larger samples begins to affect the specific sensitivity. The minimum specific activity for Cs in biota samples is about 0.062 pCi/gram at 10 per cent accuracy over a counting period of 2000 minutes. Obviously a lower specific activity can be detected if either counting time is lengthened or if accuracy requirements are less stringent, the difference being seen directly froa equation [3.4].

The measurement of sea water samples involves other considerations as the radionuclides in the water masses are highly diluted. In performing spectrometric analyses for all gamma-emitting radionuclides present at the same time, the measurement can be made on an amount of dry substance corresponding to about 7 liters of sea water only. The specific activity of concern here must be translated into pCi/liter sea wat*r suivaient. This is an extremely low level and longer counting t times, up to 5000 minutes, are necessary and a lower accuracy of 20 per cent must be tolerated. Obviously, when performing chemical treatment before spectrometry, measurements can be made representing larger sea water equivalent volumes - and thus higher accuracy can be achieved. - 73 - Table 3.10 Significant peak background count rates for various shielding arrangements

Nuclide Energy No Shielding 10 cm. Lead Plastic Bulk Anticoinc. Mode (keV) (cpm) (cpm) (cpm) (cpm)

214Pb 352 7.13 2.20 0.25 0.25

214Bi 600 5.78 2.50 0.30 0.30 511 9.56 0.66 0.61 0.04

40„ 1460 2.89 0.39 0.10 0.10

Table 3.10 lists the count rates of the main peaks for various shielding arrangements. The major natural decay peaks remain relatively significant due to the 650 liters of air enclosed by the shielding. The annihilation peak is drastically reduced by a factor xl4. Not shown in the spectrum, the K peak at 1460 keV is reduced x7 but remains siginificant since the one blank shielding wall faces a stone and plaster 40 wall and since K is prevalent in airborne dust.

When the plastic phosphor is slid forward to provide bulk physical shielding for the Ge(Li) detector, a significant drop in background results. The peaks at 75 keV and 85 keV from the lead x-rays are almost entirely removed. The major decay series peaks resulting from 214Pb and 2X4 Bi are reduced by x9. The annihilation peak however is hardly affected as high energy photons successfully pass the plastic and are absorbed in the Ge(Li) detector where the pair production process has a significant cross-section. The continuum is reduced further by an average factor x2.

Of greatest concern is the background spectrum remaining when the anticoincidence mode is in operation. The lead x-rays still appear to some extent as there is a certain solid angle for entrance into the Ge(Li) detector through the vacunan chamber.

<•'••; t - 74 -

137 In the case of Cs for example, this nuclide can be concentrated by rapid ion-exchange prior to measurement, and the determination be performed on the ion-exchange substance instead of on the entire bulk of the salt. Figure (3.16) shows the minimum detectable specific activity of sea water salts samples as a function of gamma energy 137 for the aforementioned parameters. For Cs the minimum detectable specific activity is approximately 0.17 pCi/liter sea water. The accuracy of low-level counting in the anticoincidence Compton suppression mode is enhanced by the reduction in background under peaks in question. The extent of improvement of statistical accuracy for the present system can be calculated from:

A [3.5] A-

R+2 Limit where A accuracy in a normal spectrometer A1 accuracy in a Compton-suppression spectrometer e factor by which efficiency is reduced r factor by which.peak to background ratio is improved R initia.1 peak to background ratio A Limit maximum possible improvement in accuracy for any initial peak to background ratio

The average background reduction factor is x8.5 for the system in its present state. At the pCi level the full energy peak is unaffected. From fig. (3.17) it is seen that depending on the initial (normal counting mode) peak to background ratio the anticoincidence »ode can provide'an improvement in accuracy of the peak intensity determination of nearly x3. - 75 -

3.3.4 Performance ,

As sn illustration of the system's performance a typical biota specimen spectrum is shown in fig. (3.18). '

Most peaks comprise the natural decay chains. Of prime quantitative importance however is the 137Cs. The 333 gram sample 137 was measured for 1000 minutes. The total activity of Cs is 48.5 ± 4.6 pCi, or a specific activity of 0.145 ± 0.010 pCi/gram. To be 137 noted are the wide separation of the Cs peak from the predominant Bi peak at 609 keV and the extremely low. background level under the Cs peak yielding better than 10 per cent statistical accuracy. A total of 18 individual peaks are resolved in the energy range 75 keV to 1000 keV.

Similar spectra can be accumulated for sea water and sediment samples. Essentially the same peaks are measured.

Biota samples were prepared by drying and crushing whole animals to prevent losses of elements by the usually applied ashing technique. The powdered samples are pressed into blocks by a 1-1/2 ton press assembly. Up to about 350 grams of final sample can be accommodated depending on the original form of. the sample. .

Sediment samples are prepared in a like manner. After grinding and pressing, each sample can contain up.to about,450 grams.

Sea water samples are presently measured by determining directly the radionuclides in the. total solid substance content of the sea water obtained by low temperature, low pressure evaporation. After compression of the powdered salts an average of 7 liters equivalent sea water can be prepared in each sample.

" !•';' tj't ¿ .'\ '''""',•' 'í,'', ' • 5 '''"" '"'"••' :c' . •'' - 76 -

3.4 Uptake and Loss Experiments of Zn-65 by a Prawn Palaeroon.

Palaemon elegans which is one of the most common prawns of the Palaemonidae family was selected for the experiments. The choice of this organism is based on its importance in. the marine food chain and because it is a species which can indicate pollution.

These prawns are present during.the.whole year along the eastern Mediterranean coast. The population inhabiting the shores of Israel lives in salinities fluctuating from 32% to 40.5% TSURNAMAL (1963).

Palaemon elegans has a wide geographic distribution. It inhabits the eastern coasts of the Atlantic from south-west Norway to north-west Africa. It also appears along the Mediterranean, Black Sea, and Adriatic coasts in the rock pools and lagoons. The investigation of Zn-65 uptake is of great interest because of its importance in pollution and marine ecology RICE (1963), and its role in physiology.

Zinc is released in the marine biosphere owing to fallout. It originates from neutron activations during nuclear explosions. Other sources of Zn-65 are experimental and industrial nuclear reactors which discharge their wastes into the oceans.

In the Columbia River, which is used as a coolant for the nuclear reactors of the Hanford Atomic Products,. there.is. a. reservoir of radio- nuclides among them Zn-65, the activity of which is approximately 10,000 curies of the total radioactivity of 40,000 Ci LEWIS § SEYMOUR (1963).

This nuclide is concentrated by plankton and various marine organisms because of its function in protein and carbohydrate metabolism. Zinc as a cation is found to be present in several dehydrogenases, peptidases and transphosphori lases VALLEE (1959).

The prawns for this study were collected from the rock pools of Tel Akhziv from the northern coast of Israel. Their length from the rostrum to the end of the telson was between 2.5 - 5.0 cm. In March- April the percentage of females bearing eggs. in. the total catch increased, reaching about 70-80%. At this stage of study Zn-65 «ccunulation by Palaemon, no differentiation was made between males and females. !

' : v. s : '•»

-•• ê\ï\:: - 77 -

A stock of prawns was kept in the laboratory in a glass aquarium containing sea water from the same site. Prior to the experiments, animals were adapted to the experimental conditions. The radionuclide Zn-65 was obtained as a chloride salt in a 0.1 N HC1 solution of which 10 vCi/l were added to sea water. The concentration of Zn ions in natural sea water is about 10 yg/A GOLDBERG (1957). By polarographic determination of zinc ions in sea water a concentration of 9.6 jig/1 was found. (Inst. Ruder Boskovic, Ann. Rep. July 1965 - June 1966).

The specific activity of the radionuclide used in this study was > 100 mci/mg Zn, and an addition of 10 iiCi/Jt would increase the concentration of the Zn ions in sea water about 1% only.

As a standard, a known quantity of Znr65 solution.was used and checked every day to follow the self decay of radiozinc. Background counts were also made several times a day during the investigation to check the detector.

Radionuclides which are added to the water must undergo a process of physico-chemical changes until an equilibrium is reached with respect to the already present nuclides of the same element. Our experiments indicate that a period of 70-80 hours is sufficient to reach this equilibrium with the quantity of Zn-65 added to the system. The Zn-65 accumulation in the organisms and the changes of radioactivity in the water were followed by counting the samples in a well type gaanta-ray scintillation detector with a 2 x 2 inches Nal(TA) crystal used in conjunction with a single channel analyzer system, ¿ea water for the experiments was brought from Tel Akhziv and Tel Shiqaona of the littoral area. The water was filtered through a millipore filter 0.45u pore size to remove micro-organisms and suspended particles. Salinity and pH of the water were determined at the beginning of the experiment. The salinity range was 38.50% - 39.74%. The pH range was 7.6 - 8.0. The temperature range of the water during the experi- ment was 16.0 - 19.5°C. <"

The conditions of uptake and loss experiments of Zn-65 by Palaemon are presented in Tables 3.11 and 3.12. Table 3.11 . Coaditiou of tho Uptaka ExpaxiMnt of 2»** ky »ala—o»

Bato Aquariu Ttaparatur«' Salinity* Activity No. of a La*fth MttrtaUt: No. SM Ntttr 4. »Ci/1 Spaciams (tram) () Data Mo. of Haight •c Spac.

Ifrtaka ffN 1 5 litns 16 - 17.S 3».74 7.6 10 1.95 S- S 19.12 0.45 15.12.69 2 of n 2.20 3 •attirai H 2.30 to 4 Ma H 1.90 2S.12 0.45 30.12.«$ S «atar

tfrttko froa 1 5 Utns 17.S - W.5 7.9 10 of n »1 2.3.70 2 filtm* 3 2.» 3-4.5 17.3 O.tO •4 n 00 " ps- to 3 4 1.« 2.5- 4 10.3 0.30 U.S. 70 4 M 3 2.10 3-4.5 19.3 0.65

ft« 5 lift* 17- If ».SO «.0 10 2.5.7» 7 Of M- It n 3 2.40 3- 5.5 t fllttN* 3 2.25 3 -S.S 9.3 0.« to s«a 19.3.70 9 watt» 4 2.00 3-5 5.5 0.30

«SM «qaltJMtl— i* tka tttt. Table 3.12 . CMditioas of lots bptziamt of Z»** byj

•xp*rL»M»t Oat« Aquarius Vol. of Toaporttun Salinity PH No. of «tight Unfth Mortality No. SoaNator •c *. SpociaoM (sraas) Dato No. of Rtigtt

toss froa S litors 16.S - IS 3B. N 7.7 5 3.70 3-5 2.1 2 0.90 30.12.69 7Í3N)») of H n 3.75 31.12 1 0.35 aatural 1 0.40 soa. •.1 to uator 12.1.70

toss item 5(2»S)e) S liters 17.5 - 22.5 3S.60 7.» 3 1.20 2.5 - 4.S 21.5 1 0.50 11.3.70 of >2 «attirai to . toa 2C.3.70 Motor

IM* item 10(7..)« 5 lito» 17.5 - 22.5 31.50 7.15 3 2,55 3- 5.5 20.3 1 0.Í5 19.3.70 of * natural to m 2C.5.70 wator

Palooaoa feos oqMtria 1 1 2 of «ptoko 099. Aj " * " 31*" ". "A, e) « n «243«« «m 4) - 80 -

For the uptake experiment two sets of aquaria made of transparent plastic material were used. One set was filled with 5 litres of millipore filtered and aerated sea water, and the second one with non-filtered aerated sea water. Zn-65CJL solution, having an activity of 10 vCi/l was added into the water.

In two aquaria of each set, 3-4 animals were kept to follow the accumulation of radiozinc from the water. One aquarium containing non- radioactive sea water and prawns, Palaemon elegans, was used as a control for each set of the•experimental aquaria. The survival of these animals not fed during the experiment was observed. The background activity of their total body for Zn-65 was checked. Additional aquaria contained only sea water and radiozinc to follow the behaviour of the isotope in sea water during this investigation. Sea water was sampled to measure the changes of radioactivity. 72 hours after the addition of Zn-65, Palaemon was placed in the aquaria and then removed to the counter within fixed time intervals to measure the activity accumulated.

In order to check if there was any accumulation of radiozinc on paniculate matter in sea water, 5 mi of water were filtered through millipore filters having a mesh of 0.45u and the activity of the filters was measured. The activity accumulated on the filters was negligible.

After 360 hours of the uptake experiment the prawns were removed into new aquaria containing non-radioactive fresh sea water to observe the rate of loss of radiozinc from the total body of the Palaemon into the water.

The results of the counting were expressed as counts/sec/gram of fresh weight of organism and for the water as counts/sec/mJt,

The number obtained for each sampling was plotted against time. - 81 -

The prawns for later experiments were collected at Tel Shiqmona on the 14.7.70. This catch consisted of males and females, some of which were bearing eggs. Each aquarium of the experimental set contained 4 liters of aerated and filtered sea water (0.4Sy pore size). IS uCi/4 of radiozinc were added first to the water to reach an equilibrium, and 90 hours later one prawn only was placed into each aquarium to accumulate Zn-65 from the water. The prawns were removed within fixed time intervals to measure their activity. At the same time filters containing particulate matter from the sea water and the water itself were sampled and their activity measured.

The animals were in the radioactive water about 500-600 hours. Then they were dissected and the exoskeleton was separated from the soft tissues. Their activity was determined and the results were expressed as counts/sec/grams. - 82 -

4. Results

90 4.1 Sr Content in Sea Water and Biota Samples

In Tables 4.1 and 4.2 the results of 90 Sr determinations in sea water samples from various stations are given.

Table 4.1 Sr-90 in Sea Water - Haifa Inside Bay Stations

Date of Sampling Sample Sample Collection Station Depth Volume (1967) (metres) (litres) ±O(UPC/litre)

10 11.1 1 10 22.5 0.496 0.018 11 26.1 1 10 23 0.153 0.008 26 7.2 1 10 23 0.176 0.015 45 31.5 1 10 23.5 0.233 0.14

9 11.1 3 20 23 0.310 0.018 12 26.1 3 20 23 0.167 0.015 25 7.2 , 3 .. 20 21 0.193 0.009 44 31.3 3 20 20 0.188 0.017

8 11.1 7 30 22 0.451 0.038 13 26.1 7 30 23 0.283 0.024 24 7.2 7 30 22 0.220 0.015 35 13.3 7 30 22 0.427 -0.011

6 11.1 . 10 75 22 0.382 0.009 14 26.1 10 SO 24 0.183 0.043 15 26.1 10 75 24 0.380 0.027 34 13.3 10 SO 24 0.352 0.017 42 31.3 10 SO 22 0.378 0.059 41 31.3 10 75 22 0.205 0.043 48a 28.4 10 50 21 0.400 0.018 - 83 - Table 4.2

Sr-90 in Sea Water Haifa Bay Off-Shore Stations

Sampling A Date of Sample a8s. Sample Collection Station Depth Volume (metres) (litres) ±o(uuc/litre) 5 11.1.67 11 0 22 0.308 ± 0.019 18 26.1.67 11 0 80 0.261 ± 0.018 17 26.1.67 11 100 24 0.369 ± 0.089 16 26.1.67 11 200 24 0.293 ± 0.016 20 7.2.67 11 100 22 0.157 ± 0.043 29 26.2.67 11 0 23 0.383 ± 0.016 28 26.2.67 11. 100 21 0.272 ± 0.023 27 26.2.67 11 200 25 0.103 ± 0.032 31 13.3.67 11_ 0 24 0.263 ± 0.046, 32 13.3.67 11 100 22 0.113 ± 0.028 30 13.3.67 11 200 22.5 0.165 ± 0.015 38 31.3.67 11 200 20 0.398 ± 0.023 21 7.2.67 11 200 25 0.090 ± 0.008 22 7.2.67 10 75 25 0.220 ± 0.015 56 28.7.67 11 100 25 0.386 ± 0.010 55 28.7.67 11 200 25 0.186 ± 0.006

Sr-90 in Sea Water - Cyprus Stations

60a 6.68 C-09 0 30 0.494 + 0.011 61a 6.68 C-09 100 30 0.372 ± 0.008 62a 6.68 C-09 200 30 0.368 ± 0.007 63a 6.68 C-09 300 30 ¡0.356 ± 0.008 65a 3.69 C-12 0 30 0.392 ± 0.012 66a 3.69 C-12 100 30 0.187 ± 0.007 68a 3.69 C-12 300 30 0.154 ± 0.006 69a 3.69 C-12 500 30 0.046 ± 0.006 - 84 - Table 4.3

Strontium-90 in Biota

Ash Weight Sample Species Date of Of No. Collection Analyzed (wiic/g) Biota (g)

20 Pennatula rubra 25.11.66 71.620 0.017 ± 0.002 25 Pennatula rubra 10. 1.67 75.700 Negligible 70 Pennatula rubra 3. 4.69 109.5 0.011 ± 0.001 79 Pennatula rubra 18. 5.67 48.6 Negligible 46 Charybdis longicollis 1961-1962 42.5 0.033 ± 0.002 47 Myra fugax 1961-1962 50.0 0.019 ± 0.003 17 Parapenaeus longirostris 23.13.66 31.7 0.088 ± 0.002 17 Parapenaeus longirostris 23.12.66 46.5 0.090 ± 0.001 71 Parapenaeus longirostis 9. 5.69 60.0 Negligible 76 Charybdis longicollis 2.11.61 49.9 0.133 ± 0.007 53 Sepia officinalis (shell) 7.12.67 50.0 0.036 ± 0.002 53 Sepia officinalis (muscle) 7.12.67 Negligible 22/A Sepia officinalis 7.12.66 23.200 0.050 ± 0.009 22/B Sepia officinalis 7.12.66 44.100 0.010 ± 0.002 18 Antedon mediterránea 7.11.66 53.0 0.013 ± 0.001 18 Antedon mediterránea 7.12.66 50.0 0.012 ± 0.002 24 Antedon mediterránea 9. 1.67 51.9 0.010 ± 0.002 51 Brissopsis lyrifera 6. 9.67 50.0 0.017 ± 0.004 7 Schizaster canaliferus - 109.775 0.007 ± 0.002 23 Brissopsis lyrifera 9. 1.67 120.300 0.033 ± 0.002 35 Antedon mediterránea 17. 5.67 78.2 0.005 ± 0.002 36 Antedon mediterránea 18. 5.67 48.3 0.003,± 0.001 37 Brissopsis lyrifera 27. 4.67 104.9 0.024 ± 0.002 49 Brissopsis lyrifera 8. 9.67 83,9 0.075 * 0.004 50 Brissopsis lyrifera 27. 8.65 53.2 0.070 ± 0.004 62 Astropecten aranciacus 6. 5.68 56.0 0.002 ± 0.001 21 Astropecten aranciacus 25.11.66 50.0 0.127 ± 0.019 - 85 -

1^7 4.2 Cs Content in Sea Water, Biota and Sediment Samples

In the following tables results of Cs-137 determinations obtained by Ge(Li) gamma spectrometry in various sea water, biota and sediment samples are given.

o VO CM o> t» o o 10 CM vO tO 15 VO CM r-- i-i sa r» CM «0 CM i-« O * ô O © o o o o o o O O o o o o en 41 4. •5-1 41 V 41

00 CM VO 04 en o •H 00 CM 1^ CM VO CM r"4 VO f« CM

Lvit y >Ci ) <* in CM tO to t 10 i-t m -M 10 -H t-4 41 +1 41 41 41 41 V 41

p» i-t t«. II S O vO *** vô vô vô vô e §3

m g 500 0 390 0 300 0 270 0 393 0 500 0 441 0 Tim e (mins. )

M vO o> to in I © to vO o> S vO a f-l IL — Non e

w I u to 16 0 13 8 19 9 22 0 Bkg . 21 0 25 0 20 5 Count s 19 5 28 6 31 6 34 9 26 6 26 8 Pea k Count s Non e

o o 10 0 20 0 30 0 50 0 100 0 Dept h (aeters ) Samplin g ¿1 00 70 c 60 b II 65 b •: vD S

, *-« ;•, -n

/i ,'. '" -,.' Table 4.5

Cs-137 Determination in Sediments

' - r* Peak Bkgo Time Height Activity Spec. Act. Sample Location Net Number Counts Counts Counts (mins.) Cgns) CpCi) (pCi/gm.) si; --:"V.r 210 27.8 0.122 1577 Caesarea- 332 122 1335 227 ± .012 --* V Tantura ± 2.8 Station-3 1 g

SLM-724 Caesarea- 708 322 386 2780 121 16.2 0.134 Tantura ± 1.35 ± .011 Station-6 í'

Table 4.6 137 Cs Determinations in Marine Biota

Sample Animal Peak Bks. Net Time Weight Activity Spec. Act. Number Name Counts Counts Counts (mins.) (gms) (pCi) (pCi/gm.) Brissopsis 48.5 0.145 88 388 147 241 1335 333 lyrifera* ± 4.6 ± 0.01

Metapenaeus 3.64 0.028 90 112 60 52 2000 127

•pnoceros* ± 0.89 ± .007 \.:-';<••••'>•

Brissopsis 28.5 0.186 96 291 87 204 1000 153 lyrifera* ± 2.7 + .017

Panaeus 0.017 92 55 34 21 1300 133 2.26 japonicus* ± 1.01 ± .008 OS Panaeus 4.98 0.024 •«a 86 58 35 23 1235 208 i japonicus* + 1.0 ± .008

Pënnatula < 14 < 0.08 None 35 None 1300 162 87 rubra* ± 1.4 ± .008

Portunus < 12 < 0.08 "•.'. None None 1000 152 89 nastatus* 85 ± 1.2 ± .008

Sepia 91 211 < 11 < 0.05 officinalis* None 62 None 2000 ± 1.1 ± .005 (muscles)

* Invertebrate ** Fish

Table 4.6 (cont'd) Table 4.6 (cont'd)

Saaple Animal Peak Bks. Net Time Weight Activity Spec. Act. Nupber Nane Counts Counts Counts (mins.) (gms) (pCi) (pCi/gm.) Charybdis 102 92 2.50 0.028 longicollis* 36 56 2600 90.5 ± 0.50 ± 0.006

91 Sepia officinalis* 74 28 46 2000 245.5 6.8 0.028 (shell) ± 1.6 ± 0.006 Parapenaeus 0.05 93 57 16 41 1515 50 2.50 longirostris* ± 0.52 ± 0.01

105 Pennatula 76 48 6.05 0.033 00 rubra* 28 2000 97.2 ± 1.13 ± 0.007 09

Siganus 19 1.67 0.019 106 luridus** 47 28 1360 88.4 ± 0.77 ± 0.08

Sardinella 24 7.4 0.065 107 aurita** 96 72 1344 113.9 ± 1.05 ± 0.009

Mugil 11.2 0.047 108 cephalus 121 42 79 1700 238 M. capito** ± 1.8 ± 0.007 Sardino 6.93 0.054 109 pilcardus** 136 42 94 2000 127 ± 0.88 ± 0.007 Sardinella 14.6 0.072 110 aurita** 151 42 109 1650 204.6 ± 1.9 ± 0.009

* Invertebrate ** Fish Table 4.6 (cont'd)

Sample Animal Peak Bkg. Net Time Weight Activity Spec. Act. Nunber Name Counts Counts Counts (mins. ) (gms.) (pCi) (pCi/gm.D

Pennatula 105 76 48 2000 2.8810.52 rubra* 28 97.2 0.029±0.005

Parapenaeus 93 57 16 1515 2.5 ±0.5 longirostris* 41 50.0 0.050±0.010

Charybdis 102 92 36 56 2600 90.5 2.5 ±0.5 0.028±0.006 longicollis* -, "S

Sepia 91a 74 28 46 2000 245.5 5.1 ±1.4 0.021+0.006 officinales*

Astropecten • •. s --•• .\>l 457 350 107 5000 0.195 ±0.052 0.004+0.001 103 aranciacus* 43.4

Sardinella 107 96 24 72 1344 113.9 7.40 ±1.05 0.065±0.009 aurita**

Sardina 109 136 42 94 2000 127.0 6.93 ±0.88 0.054±0.007 I pilchardus** 00 Siganus 106 47 28 19 1360 88.4 1.67 ±0.77 0.019±0.008 luridus**

114 Boops boops** 305 80 225 2820 91.7 9.39 ±0.82 0.102+0.009

108 Mugil sp. ** 121 42 79 1701 240.6 11.2 ±1.8 0.047±0.007

113 Sphyraena sp.**329 128 201 2780 100.2 9.11 ±0.97 0.090±0.010

Upeneus 31 16 15 1120 121.0 1.92 ±0.89 0.016±0.007 111 •oluccensis**

* Invertebrate ** Fish - 90 -

4.3 Experimental Studies on the Uptake and Loss of Radioelements

Experimental studies for evaluation of accumulation factors are carried out in view of the fact that marine organisms accumulate radionuclides to different degrees and at different rates.

The filter feeding animals take in a larger quantity of radionuclides which are adsorbed at the surface of organic and'inorganic particles suspended in sea water. The chemical form of the element in the environment is an important feature in the ability of the organism to retain it in the 1)ody tissues. The levels of radioactivity of the majority of species may be expressed as a fraction of the levels found at the same station and at the same time in the indicator species. Biological indicators of ''particulate radionuclides" were found in the Windscale area MAUCHLINE AND TEMPLET»! (1963). This method of comparison* if verified in a time series, will lead to a restricted number of species to be investigated. The importance of this may be stressed in tropical and subtropical waters with an extensive variety of species, which is true for the eastern Mediterranean.

The specific activity of sea water will vary seasonally as a result of the hydrographie conditions. The existence of a thermocline which varies in depth and stability will affect the distribution of the various radionuclides in relation to space and time. Direct transport of radio- nuclides by currents was observed in Pacific waters. The seasonal fluctua- tions of the phytoplankton, Zooplankton, benthos and fishes affect the concentration of various radionuclides. The spring and autumn peaks in the plankton abundance and its specific composition will influence concentra- tion of radionuclides uptaken by means of biological processes and physico- chemical adsorption KETCHUM (1957). The accumulation of radionuclides in marine biosphere is dependent upon the chemical characteristics of the water. The most important parameters are temperature, salinity, pH and the presence and nature of complexing agents KRUMHOLZ et al., (1957). RICE and MURDOCH (1963) proved that temperature and salinity have an effect on the accumulation of radiocobalt by the brine shrimp Artend* , in experimental conditons. - 91 -

The uptake of Zn-65 by phytoplankton seems to be affected by light as shown in the experiments carried out in the Laboratory of Marine Radiobiology, Rovinj, KECKES et al., (1964).

The elements present in marine environment are accumulated by the organism through chemical and physiological processes. The accumulation of radioactivity occurs due to incorporation of radioactive isotopes together with radioactive isotopes of a certain'element in the body tissues. The isotopic effect influencing the chemical and physical behavior of various isotopes of a certain element, when dealing with processes of accumulation by marine organisms, can be neglected. Large scale experiment is carried out in the Windscale area where radioactive effluent is discharged into the marine environment and studies carried out on the accumulation of fission products by marine biota,. MAUCHLINE et al. (1964).

On the coast line of Windscale, the colonial polychaete, Sabellaria builds tubes from sand particles which are contaminated by radionuclides e.g. Ru-106, Zr-9S/Nb-95, Ce-*144. In this area, the radioactivity on the sea bed was found to be associated with pockets of fine mud and with organisms present in the same areas and was mainly due to Ru-106, MAUCHLINE and TEMPLETON (1964). This element is adsorbed to silt particles which form a surface much larger than the organic particles. In experimental studies it was shown that the accumulation of Ru-106 from the water by the lobster was much more rapid than from the food,TEMPLETON (1961).

Laboratory experiments on the uptake of radionuclides, e.g. Sr-89, Sr-90, Cs-137, Ru-106, Zn-65, by marine organisms were carried out in various laboratories. BOROUGHS et al., (1957) discuss the results obtained at the Hawaii Marine Laboratory and Fishery Radiological Laboratory, Beaufort, North Carolina. Marine teleosts concentrate radionuclides from food organisms composed of Zooplankton. Copepods (Tigriopus) become radioactive due to ingestion of radioactive phytoplankton cells and other suspended particles. The accumulation of Zn-65 and Co-60 by copepods from sea water is rapid and amounts to high concentrations, as proved*by experimental studies. They failed to accumulate significant amounts- of fission product radionuclides e.g. Cs-137, Sr-90,CHIPMAN (1958). - 92 -

The accumulation of radioactive materials by teleosts occurs by means of adsorption and absorption from the sea water or by means of ingestion. Experimental studies show that Zn-65. was accumulated by marine fishes to a larger extent from food than from sea water, RICE (1963).

The marine biosphere tends to-concentrate heavy metals, e.g. Cu, Zn, Ni, over the hydrosphere by factors of up to 106 on a weight- for-weight basis. These elements form stable complexes with organic chelating agents, GOLDBERG (1957). The accumulation of radionudides with special reference to the heavy metals is discussed by TEMPLETON (1961). The uptake and accumulation of Zn-65 by marine organisms was studied by CHIPMAN et al.,(1958). The work covers various levels of the marine food-chain, e.g., phytoplankton, molluscs and teleosts. The marine diatoms accumulated considerable- amounts of Zn-65 which remained in the cells to a large extent, though zinc present in the cells is exchangeable with that of the water. The shellfish accumulated Zn-65 from the surrounding sea ./ater probably because of the great difference between zinc content of the water and that of the organisms. The fish excrete this radionuclide after the uptake- through the digestive tract. However, certain internal organs show accumulation of Zn-65 which is slow and long continued.

The molluscs which are filter feeding animals, concentrate in the digestive tract, radionuclides occurring in the phytoplankton. This process depends largely on the physical state of the nuclide in the water and the physiological demand for the element of the molluscs. The ionic radionuclides pass readily through tissue membranes while the particulate form is associated by means" of adsorption to the body surfaces. The giant clam Tridacna- concentrates Co-573 Co-58, Co-60 and Nh-54 in the internal organs, WEISS and SHIPMAN" (1957).

Some of the elements accumulated by marine organisms are involved in metabolic processes, the others uptaken-directly fro« the Water, sediment or food, do not seem to have any metabolic significance. This fact was observed for a series of heavy metals, the role of which — in the-physiology of the organisms- --is" unknown. - 93 -

It was proved in the laboratory that EDTA depresses the uptake of Zn-65 by the clam Mytilus and fastens its loss. The same was also true for Co-56, Co-57 and Co-58,the uptake of which from the sea water by the shrimp Palaemon was considerably inhibited in the presence of EDTA. The influence of increased iron, cobalt and zinc concentration on the uptake of cobalt and zinc radionuclides by shrimps and mussels was previously studied. The results show that iron enhances the uptake of radiocobalt in mussels but no such effect was observed for the shrimps, KECKES et al., (1964).

The uptake of radionuclides may be represented as an exponential process in which the time required to reach an equilibrium is a function of weight of the organism, MORGAN (1963). In nature, the organisms tend to reach an equilibrium state in which the ratio of radionudide to stable element remains the same as in the environment. It is instructive to conduct experiments in conditions peculiar for each Zoogeographie region. The Levantine Basin of the Mediterranean is inhabited by characteristic populations of animals which are to a large extent of Indo-Pacific origin, and form an example of a tropical environment with a relatively low productivity.

4.3.1 Uptake and Loss of Zn-65 in Palaemon elegans

In general, the incorporation of Zn-65 in the body of the prawns Palaemon elegans was fast. After a period of 75-100 hours most of the total activity was gained. Later and up to 360 hours the uptake was slower and it seems that an equilibrium was reached. The radioactivity level in sea water due to Zn-65 was found to fluctuate very little, both in aquaria containing Palaemon and the control aquarium. The small changes in activity expressed in counts/sec/ml of sea water were the result of measurement technique. These fluctuations cannot be accounted for the different rates of the organisms. The different shape of the curves obtained in uptake and loss experiments indicates that the rate of accumu- lation of radiozinc was faster than its loss. - 94 -

The second part of our study refers to the difference in accumulation of Zn-65 between males and females of the prawn Palaemon elegans. We also tried to determine the distribution of radiozinc in soft parts of the body and in the exoskeleton by dissection of the animals.

In the brine shrimp Axtemia salina which was fed on phytoplankton containing Zn-65 there was a great difference in the concentration factors for males and females, RICE (1963). Male Artemia had a concentration factor of 76, while the female concentrated Zn-65 times over amounts in the medium. CROSS et al., (1968) found out that Zn-65 appeared in the exoskeleton and present in its inner layers in the benthic anphipod Anonyx sp., and in the suphausiid Euphausia pacifica. Another area of high concentration of Zn-65 was muscle tissue. In this study the deter- mination of Zn-65 was done by the technique of autoradiography.

During the experiment three of the prawns underwent molting and females which were bearing eggs released them, and they were scattered in the water. The exoskeletons were taken out from the aquaria and preserved. They reached a very high level of activity in relation to the total activity of the entire body. This is an indication for a rapid accumulation of Zn-65 on the exoskeleton. It is expected that the rate of accumulation will be different because of the morphological and physio- logical changes as a result of the molting, due to an increase in dimen- sions, formation of new tissues and hardening of the new exoskeleton.

The results obtained indicate that Zn-65 concentrated to higher levels by the exoskeleton.than by the soft tissues of the Palaemon.

Seven aquaria of transparent plastic material were later used for an experiment in which one adult female was kept in the contaminated water. The salinity.of the filtered sea water was 38.40%o and pH 8.3 before the start of the experiment. An aquarium was used as a control to check the behaviour of Zn-65 in filtered sea water without the interference of Palaemon. - 95 -

The salinity range of the water used in the experiment was 38.7 - 38.9%e and pH 7.6 - 8.2. The prawns were kept at a temperature of 22°C which was constant throughout the experiment and the maximum time was established as 600 hours. During the experiment the prawns moulted and the exoskeletons (ecdysis) were counted for the activity due to Zn-65. Of the total seven Palaemon prawns four survived until the end of the experiment.

The uptake curves were calculated for the animals which showed a regular pattern as observed in the previous experiments carried out in March 1970 at a lower temperature of 16 - 19.5°C. The curves reach an asymptote at about 200 hours. (Fig 3.19).

The curves which were obtained from ' experiments are irregular and cannot be regarded as characteristic for the Zn-65 uptake by ipalaemon. Some of the irregularities can be possibly explained by the moulting process, which caused a considerable decrease in the activity of the prawns due to loss of the exoskeleton in which adsorbed zinc was retained.

After dissection of the Palaemon at the end of the experiment the ratio of the activity due to Zn-65 of the muscles and exoskeleton was established.

Activity (counts per second) of exoskeleton as compared with the muscles

of Palaemon after 600 hours in sea.water contaminated with Zn-65.

Exoskeleton(E) Muscles(M) Ratio E/M

162 c/sec. 219 c/sec. 0.74

253 " 107 " 2.36

274 " 241 " 1.14 - 96 -

From data presented above it may be inferred that the ratio of Zn-65 adsorbed to the exoskeleton to that incorporated in the body, varies considerably. This needs further investigation in order to express quantitatively the fraction of zinc metabolized, as compared to the amount adsorbed to the external and internal tissue surface. - 97 -

The uptake curves of Zn-65 by Palaemon elegans at different temperatures

The effect of temperature on the uptake of Zn-65 from sea water was studied. In aquaria containing the same amount of 10 yCi/i, of Zn-65, experiments were performed, as previously described with the prawn Palaemon during different seasons of the year. The results presented in fig.(3.21) were compiled for the periods: December 1969, March and July-August 1970. In these experiments the mean tempera- tures were 16.5°C (range 16-17°C) during 15 - 30 December: 18°C (range 17-19°C) during 2-19 March 1970; 22°C during the period 20 July to 14 August 1970.

It may be inferred that the temperature of the sea water has an effect on the rate of uptake of Zn-65 by the prawns. The increase in temperature causes a more rapid uptake of Zn-65, though the shape of the curves does not change significantly, and the asymptote is reached close to 200 hours after start of the experiment.

The effect of temperature on concentration or radionuclides is mentioned by POLIKARPOV (1966) referring to the concentration factors of iodine-131 by the mollusc, Dreissensia polytnorpha. The temperature affects the uptake of fission products from an aqueous medium, through its effect on the rate of biological processes. The concentration factor of Zn-65 by Palaemon was calculated for most experiments and expressed as activity in counts/sec/gram in relation to counts/sec/mÄ of ambient sea water. In most cases a straight curve could be fitted in a diagram in which x = log hours and y = log c.f. (concentration factor).

Some of the results showed scattered points, however, in all cases the concentration factor after 200 hours was found to be within 50-70 times that of sea water at the time when the equilibrium is reached and the uptake of Zn-65 becomes insignificant. The results of a concentration factor versus time for 2-19 March 1970 are presented in fig.(3.22), and are compiled from experi- ments in two aquaria.

The concentration factors of Zn-65 in oysters are discussed by ROMERIL (1971) and refer to various tissues of two species which are referred to in the discussion. - 98 -

Vertical migrations of small nektonic organisms may result in a net transport of elements from areas of high to those of low concentration. The migrations are caused by diel vertical movements of animals which take up radionuclides and cause their redistribution in different water layers. In the above mentioned study the seasonal variations in the Zn-65 per gram of biomass of micronekton were followed, with the result that the Zn-65 per gram wet weight was the same/ at all depths during the winter. However, the Zn-65 activity was ten times higher in the water layer between surface and 150 metres. These seasonal variations, however, were not related to the presence of a permanent h'ilocline which exists during summer and winter in the waters off Oregon, but . to the variation of metabolic requirements for zinc of the migrating species.

The experiments an the accummulation of Zn-65 in the exoskeletons of Euphasia pacifica demonstrate that the vertical transport of this radionuclide may be a function of the sinking rate of exoskeletal material which became radioactive, and the rate of exchange of activity with water. The radio- activity will be transported towards the bottom in waters shallower than 300 m and if eaten by benthic species, may enter the food chain of the organisms living on the sea bed FOWLER and SMALL (1967).

X •;;-.. ,-iWiw^î T^7

"•ï,"."-"?"", -. ; 'ü"'1;

- 99 -

4.3.2 Uptake of Zn-65 by Tapes decussatus

A series of experiments were carried out on the uptake of Zn-6S by the clam Tapes decussatus in laboratory conditions by the present author, GILAT (1971).

The work was carried out during the stay in the IAEA International Laboratory of Marine Radioactivity at the Océanographie Museum of Monaco (October, 1969). The facilities were arranged by Dr. Keckes S., then Staff Member of the Laboratory and with kind support and permission of Dr. J. Joseph, Director.

The clam Tapes was kept in a plastic basin with millipore (0.45y) filtered aerated contaminated sea water with Zn-65. The specimens were collected in the vicinity of Monaco in the coastal area, placed for acclimatization in pure sea water for a period of several days in a constant temperature room of 14°C. The animals were marked (in total eight specimens) to follow the uptake of each specimen separately. They were starved during the experiment but survived the period of about 200 hours and were left in good condition at the end of study.

At the beginning of the experiment the weight (fresh) of each specimen was established. The activity of the 4 liter basin was 20 uCi at the initial stage and since the experiment was short no correction was made for the physical half-life of Zn-65.

The counts of Zn-65 activity were carried out after removal of each animal into a plastic tube in a well-type scintillation counter with a Nal(TA) crystal detector. The mean activity of the total number of eight specimens of Tapes decussatus was calculated for the intervals of: 1, 3, 6, 12, 24, 48, 72 hours of the counting.

It is common that in a set of such measurements of activity some values depart from the average by an abnormally large amount. Then a mean value closer to the true value could be obtained if suspected values were rejected from the set. CHAUVENET's criterion was used in this experiment and the curve obtained representing, the uptake of Zn-65 by Tapes. (Fig 4.1). - 100 - Since water samples of 2 ml of non-filtered sea water were taken for counting at the same intervals in which the activity of Tapes was followed» concentration factors were calculated for the clam representing the ratio of activity per gram of body to that of the sea water. (Fig 4.2). From the experiment it may be inferred that the uptake of Zn-65 by the clam Tapes is a relatively rapid process but the equilibrium is not reached within a period of days.

In experiments carried out by KECKES et al., (1969) the concentration factor of Zn-65 was calculated for soft tissues and shells separately in the presence of EDTA. In these experiments it was also verified that the uptake of radiozinc by the mussel, Mytilus galloprovincialis, in laboratory experiments, is rapid but the equilibrium is reached after a long period. The uptake for the soft tissues was about ten times higher than for the shells. In the Mediterranean Sea experimental studies on the uptake and loss of Zn-65 by the mussel, Mytilus galloprovincialis were performed in laboratory, where the animals were kept in plastic basins with aerated sea water to which one yCi/liter of Zn-65 was added, KECKES et al., (1968). It was realized that the loss of zinc-65 is a slower process than its uptake. The incorporation of this nudide in the mussels was fast but the equilibrium was reached after a long period. The uptake rate was ten times higher for the soft tissues than for the shells.

The initial higher loss can be possibly attributed to the removal by exchange of the radiozinc adsorbed on the free surfaces of the animals, since the firm bonds are formed within the proteins and crystal lattice of the shelL

The accumulation and loss of zinc by oysters, Crassostrea gigas were carried out in their natural habitat. The animals were exchanged between two areas at the Pacific coast in which the amount of Zn-65 differed considerably. Zn-65 from worldwide fallout occurs in both areas; in experimental studies, however, in Willapa Bay, north of the Columbia River mouth the values of Zn-65 in oysters of Willapa Bay (where the amount' of Zn-65 is increased due to the Hanford reactor effluent) were 85 times greater than in the Puget Soúnd-Hood Canal, oysters,close to Seattle. 1J J , ' ' •. ' •, .'- ' A.\.

- 101 -

There are many factors that affect the metabolism of Zn-65 by oysters; the amount of zinc, temperature, light, salinity, which are factors which enhance or depress zinc uptake.

The physiological factors: age, size, growth rate, stage of maturity, largely account for the variability of zinc accumulation by individual animals, SEYMOUR (1966). The accumulation of Zn-65 by oysters transferred to Willapa Bay is not a simple exponential relationship, it may be regarded as a two or more compartmental system. The loss of Zn-65 by oysters transferred from Willapa Bay to Puget Sound was followed for a period of about 600 days and the measurements of activity were expressed in picocuries of Zn-65 per gram of dry soft body weight. The effective half life was established - 135 days and the biological half life - 300 days, SEYMOUR (1966). The explanation of two-compartmental system for Zn-65 accumulation, with the assumption that zinc is either exchangeable or tightly bound is contradictory to the shape of the loss curves, which, though representing various inflections for individual lots of oysters, can be best represented as a straight regression line common to all lots.

These data are different from those obtained by KECKES et al., (1968) in the laboratory experiment on Mytilus, where a multicompartmental system is used to explain the kinetics of zinc metabolism in mussels. The distribution of Zn-65 in the marine biosphere is of importance since its presence results from the neutron-activation during weapon tests and from reactors. This nuclide was found prominent in plankton, fishes and birds near Eniwetok shortly after 1956 explosions. Zn-65 proved to be the most conspicuous artificial gamma-emitter in marine animals off the Oregon Coast. The relatively high amount of Zn-65 near the mouth of Columbia River originates from the activation of stable zinc. The input of this nuclide to the Pacific has been calculated to be 30 curies per day, YOUNG and FOLSOM (1967). - 102 -

In the above described experiment YOUNG and FOLSOM (1967), the mussel Mytilus californianus, which is an intertidal species was moved to an environment not contaminated at Scripps Pier, from their natural habitat in the Columbia River mouth where they concentrated the Zn-65 from the sea water.

The results of the experiment with Mytilus presented in fig. 1, p. 441, in the above cited paper, show the rate of decrease of Zn-65 in the soft tissue and shells during one year. The results are given in picocuries per kg wet weight of about 300-500 grams of tissue. It may be inferred from Table II in the same paper, which summarizes the distribution of Zn-65 in various tissues that the nuclide was concen- trated mainly in kidney, digestive glands and muscles, less in gonads and gills forming a total of 96% of Zn-65 while in the shell only 4% were assimilated.

The effective half life in the sott tissues was found to be 58 ± 2.7 days, after correction of the biological half life by combina- tion of biological and radioactive half lives of 76 and 244 days, respectively. - 103 -

5. Discussion

In discussing the results of this study we will first consider the levels of contamination of the water masses and certain groups of organisms with respect to Sr-90 and Gs-137.

•Hie Sr-90 levels were determined in coastal waters in several stations of the Haifa Bay during January to March 1967. The Sr-90 levels in the upper water layer between the surface and down to the depth of 30 metres range between 0.17 - 0.50 pCi/A. In the intermediate water layer between 30 to 200 metres the range of Sr-90 was 0.18 - 0.40 pCi/A.

These values can be considered as typical for the continental shelf of Israel in the eastern Mediterranean. The data on Sr-90 content in the Mediterranean Sea are scarce and limited to the waters of the Ligurian, Tyrrhenian and Adriatic Seas TASSI PELATI and TRIULZI (1969). The level of Sr-90 in the Ligurian Sea in the surface waters were determined in 1964 - 1.26 pCi/A; in 1967 - 0.04 pCi/A and in 1968 - 0.14 pCi/iL In the North Adriatic Sr-90 levels were in 1964 - 1.53 pCi/A and in 1965 - 0.42 pCi/A. In the Tyrrhenian Sea Sr-90 levels were in 1963 and 1964 0.42 pCi/£ and 0.60 pCi/A respectively.

The closest area outside the Mediterranean for which values of Sr-90 . were determined is the Black Sea. In I960 - 0.13 - 0.27 pCi/A SHVED0V et al (1966).

In the open Atlantic in 1966 the annual mean values of Sr-90 concentra- tion in surface waters was found to be in the 10° - 20° latitude band - 0.08 and in the 50° - 60° latitude band - 0.1 pCi/A BOWEN et al. (1968).

An attempt was made in Japanese waters to find an index for the change in Sr-90 concentration in several marine organisms: algae, Zooplankton, starfish, molluscs and fish FUKAI (1964).

Measurements of Cs-137 were made in an installation situated 120 miles north of Scripps Institution; it collects sanitary sewage from Los Angeles and dispenses the treated material into the open sea. In 1960 the values were - 0.19-0.48 pCi/g raw sewage. Cs-137 concentration of the local surface sea water was at the average 0.1 pGi/Jl in the sewage, FOLSDM et al (1960). ' ' (t; ! -

- 104 -

In our waters the following values were obtained for Sr-90: the Indo-Pacific crab Charybdis longicollis which penetrated through the Suez Canal to the Mediterranean - 0.133 yyC/g of ash in a sample taken in November 1961. The shrimp Parapanaeus longirostris examined in May 1969 contained negligible quantities of Sr-90. The samples analysed contained 49.9 and 60.0 grains of ash.

The highest values for Sr-90 were obtained for the sea urchin Brissopsis lyrifera, collected in August 1965 and September 1967. The contents were 0.070 and 0.075 yyC/g of ash respectively. These are animals which live in the sea sediments and have a shield of calcium carbonate.

In some samples e.g. April 1967, B. lyrifera contained 0.024 pyC/g ash and in January 1967, 0.033 yyC/g. Another sea urchin, Schizaster canaliferus contained only 0.007

Lowest values were obtained for the sea pen, Pennatula rubra - 0.017 and 0.011 uuC/g ash in 1966 and 1967, respectively.

The lowest values obtained for the sea lily Antedon mediterránea- in May 1967 - 0.003 to 0.005 uwC/g ash.

The highest concentration of Sr-90 was found in pike bone from Lake Rogen (Sweden) - 20.400 pCi/kg. The corresponding water concen- tration - 2.4 pCi/A. The lowest concentration - 50 to 110 pCi/kg is found in pike bone from Tvären. These values were obtained during 1960 - 1965 and are in good agreement when negative correlation between high uptake values and high electrolytic conductivity in the water are considered, AGNEDAL (1967).

The vertical penetration of Sr-90 and Cs-137 in sea water in the open Pacific was observed in June 1954. Recently the penetration of radionuclides was observed down to 5000 metres depth. The difficulty of penetration of radionuclides through the thermocline into deep layers was observed. The same ratio of Cs-137 and Sr-90 in deep water as compared with surface water suggests that there was no biological separation of both nuclides, MIYAKE et al. (1962). In our waters the penetration of Cs-137 was observed to the depth of 1000 metres, which was the deepest layer sampled (Table 4.4). The decrease was from 0.79 pCi/Ä to 0.16 pCi/£;at the station situated between our coast and Cyprus. - 105 - Sr-90 on the earth surface :

The estimate is that 13 MCi of strontium was distributed over the earth in January 1967. The strontium-90 inventory in that period was: in stratosphere - 0.3 MCi in troposphere - 0.1 MCi HARDY et al. (1968) global deposit - 13.0 MCi

Heaviest fallout was in the northern hemisphere with the peak between 30° - 60° N latitude. Deposition was lowest in the polar equatorial regions with a small rise between 30° - 50° S latitude. The peak of the southern hemisphere was about one fifth that of the northern hemisphere. The cumu- lative deposit of Sr-90 in the northern hemisphere was 10.7 MCi and in the southern hemisphere 2.3 MCi, making a total of 13 MCi. Some fraction of this amount of Sr-90 will eventually become available to biological systems.

Overland data in Israel for Sr-90 levels from the period 1957 - 1962 2 ranged approximately between 3.5 pCi/A - 30 uCi/í. in rain water and 14 mCi/km - 30 mCi/km2 in soil'GILAT.'(1961).

Sr-90 data in rain water collected over the land in winter Qàovember- December) 1957/58 are within the range of 1.6 - 5.5 pCi/A; the average values were found to be 3.5 pCi/A. In February 1959 the concentration of Sr-90 in rain water rose to 30 pCi/Ä GILAT (1961).

During the year 1967 the Sr-90 overland data in Israel were between 0.1 to 13 pCi/fc in the Banias River. In vegetation these values were 1 to 3 pCi/gram ash.

The surface activity in soil ranged from 2-73 pCi/km PROULOV and SHALMON (1969). Available overland data are relatively scarce to enable quantitative comparison with our sea surface water data.

:¿ - 106 -

The results obtained in our studies show relatively little fluctuation in the content of Cs-137 in various invertebrates.

The Cs-137 content in Echinoderms: Brissopsis lyrifera - 0,145 to 0.186 pCi/g dry weight. The lowest value was obtained in the crab Portunus hastatus - 0.08 pCi/g of dry weight. The shrimps Penaeus japonicus, Metapenaeus roonoceros, and Parapenaeus longirostris contained also low quantities of Cs-137, the latter - 0.05 pCi/g.

Some of the fishes were more contaminated than the invertebrates (Decapoda) especially Sardinella aurita - 0.065 to 0.072 pCi/g; Sardina pilchardus - 0.054 pCi/g; Mugil sp. - 0.047 pCi/g; Upeneus nioluccensis - 0.016 uCi/g.

The first two species mentioned above are pelagic, spending most of their life history in the water layers, above the bottom. They also feed mostly on Zooplankton from which the passage of radionuclides is possible through the food chain.

Species living on the sea bed e.g. Mugil and Upeneus take up the Cs-137 from the sediments and the organic matter, as well as from the benthic algae and invertebrates.

The species Boops boops forms an exception, containing 0.102 pCi/g. This fish migrates moving vertically and is taken in all water layers, down to the bottom (Table 4.6).

The concentration factors (c.f.) for Cs-137 in red algae, muscles of higher crustaceans, molluscs and fishes range from one to several tens of units. With few exceptions, data are similar for the Pacific, Atlantic, Black and Barent Seas. The concentration factors of Cs-137 for bottom material on the continental shelf are measured in hundreds of units.

In decapod crustaceans Cs-137 cf. for total body are within the range of 4 - 8 in most species. A higher value of 15 was obtained for Palaeaon in experimental studies. Most of the^molluscs have concentration factors within the range of 6 - 12. Fishes living on the sèa bed e.g. Pleuronectos platessa show a total body concentration factor of 6 - 7.POLIKARPOV (1966). - 107 -

In our waters the concentration factor for the most contaminated fish Boops boops is 12-13, calculated for the continental shelf. Other fishes show much lower concentration factors for Cs-137 in nature.

Sardinella aurita which is a typical pelagic species had a concentration factor of 8. The order of magnitude is in good agreement with the values obtained for the fish in other seas.

Radioactive contamination of flatfish in the North Sea was investigated in June 1963. The values for Sr-90 were 0.33-0.37 pCi/g. Ca and Cs-137 was calculated in pCi/g K. The values for Cs-137 were 6.4-7.1.

The contamination in the coastal area of the German Bight was different from that in the North Sea. Sr-90 values fluctuated between 0.2-1.3 pCi/ of water, while the flatfish contained 0.2-2.59 pCi/g Ca. Processed fillets had 0.024-0.180 pCi/g ash of Sr-90. Cs-137 values were in the surface water - 0.6-1.4 pCi/&, while in the flatfish - 0.4-37.0 pCi/g K.

These values were obtained during the period 1961 - 1964 with a clear trend of increase within that period, FELDT (1966).

Except in the muscles of the herring (Clupea) , where a high stable cesium content was found, concentration factors for marine species are in the order of 10-10 , while in marine fish the value of 103 is reached. The concentration factors are independent of the sea water cesium i.ntent.

The factors which affect the rate of radiocesium absorption are.species differences in decapod crustaceans. The pelagic species of fishes show a higher uptake rate than the demersal species. Radiocesium is readily absorbed from food, BRYAN et al. (1966). These conclusions were drawn mainly from data collected during field studies at Windscale (United Kingdom), where results from field work were combined with laboratory experiments. •

\ - 108 -

Uptake and loss of Zn-65

The combination of zinc and polysaccharides has been suggested as a possible mechanism for its uptake by the brown seaweed Laminaria digitata BLACK and MITCHELL (1952), BRYAN (1969).

Portugese oysters Crassostrea angulata of length 6.4 - 7.6 cm and native oysters, Ostrea edulis, were used in uptake studies at 10°C without feeding, in unfiltered sea water. Zn-65 (zinc chloride) was added to a concentration of 1.77 x 10 uCi/mÄ and with carrier the zinc concentration was 10~ ppm; the tank water was changed weekly, Zn-65 loss to tank walls was negligible.

The effect of stable elements: iron as ferric chloride and cobalt as cobaltous chloride, on the Zn-65 uptake was studied, when their concentra- tion was equal to that of zinc, i.e. 10 ppm.

Analysis of data using equation:

C = - e"kt)

C - concentration at time t A - calculated equilibrium concentration factor k - biological decay constant for Zn = 0.693/t1/2 65 Zn/g tissue Concentration factor - 65, Zn/g sea water Zn-65 is accumulated in mantle and gills of Ostrea edulis, the biological half lives are very similar for all tissues. The highest'concentrations : mantle: 800 over sèa water , gills: 1,000 over sea water after 6 weeks. The heart and kidney occupy an intermediate position. The adductor muscle accumulated least: 160/ sea water. A plot of the intake rates of tissues against their stable zinc levels at the start of the experiment, produces a straight line, where the intake is related to the zinc level/g tissue. - 109 -

The most noticeable difference between the uptake of Zn-65 by 0, edulis and C, angulata is the wider range of biological half lives for the latter species.

The principal effect of iron and cobalt on the uptake of Zn-65 by native oysters Ostrea edulis is to depress the rate of uptake of Zn-65. The final concentrations of Zn-65-in the shell, are significantly depressed in the presence of stable elements.

Localization of Zn-65 in subcellular components.

The distribution of radioactivity was measured in subcellular fractions of thé mantle, gills, heart and visceral mass in sea water with Zn-65 during 24 hours. The major portion of radioactive zinc was associated with the fraction consisting of nuclei and all debris.

This study has demonstrated that the pattern of Zn-65 accumulation in Crassostrea angulata and Ostrea edulis is similar to that absorbed in other oyster species. The accumulation is greatest and fastest in those tissues (e.g. gills and mantle) which are in closest contact with the sea water, and to a lesser extent in other tissues«

Mechanisms postulated to explain concentration of trace metals by marine organisms : a) adsortpion of ions at membrane-water interfaces b) absorption by diffusion of metal ions across semi-permeable membranes c) ingestion of ions with food or in combination with particulate matter; absorption through the gut wall.

The intake rates of various tissues may reflect the relative involvement of a) and b) in the uptake process. It is assumed that accumulation process c) is very small for Zri-65. The adsorption process contributes significantly, involving direct combination with the tissue epithelium or with mucus layer covering these organs. This layer consists of coi|iplex carbohydrate sulphates with possible ion exchange properties, thus facilitating a rapid exchange across the cell membranes. 1

; %t -.V -1 • -Ji^ îjj-* l, • - 110 -

In the environment, equilibrium values are greater and the biological half lives very much longer. The absence of an ingestion pathway for Zn-65 under the experimental conditions may have a profound effect upon the uptake mechanism. The filtering of particulate radioactive material represents a high specific activity source of Zn-65 and its absence would.lower the equilibrium concentration and possibly the biological half life.

The uptake of cesium-134 by plaice and rays from water alone, results in a much lower equilibrium concentration than both from water and food. The importance of taking into account the different physico-chemical forms in which zinc exists in sea water was stressed in literature; it was found that the rate of uptake of stable zinc from the environment was different significantly from that observed for radioactive zinc in experimental studies. The experiments with tissue homogenates have demonstrated that a major part of radioactivity is associated with less important debris fraction. Preliminary studies on columns of gel by filtration have shown that about 60% of Zn-65 in the supernatant of mantle and gills is associated with protein fraction; no attempt was made to fractionate the proteins further.

Zinc in biological systems is required as & constituent of oxidation- reductions hydrolytic and lytic enzymes. Many marine organisms car* concen- trate zinc from ambient waters and it is of interest whether zinc is needed immediately to satisfy metabolic requirements, or is in excess of their needs.

Marine plants consume the element from sea water, while the animals obtain it by the food chain as enzyme bound zinc. Measured concentrations of zinc in marine plants and animals vary considerably among organisms, but are in all cases much higher than the calculated zinc requirement. Only benthic algae (sea weeds) were presented in a table titled: "Measured concentrations of zinc in marine plants and animals1'. Other systematic groups: Coelenterata; Crustacea (Amphipoda, Decapoda); Mollusca; Echinodermata; Chordata (Pisces). - Ill -

The data are in ppm Zn/wet wt. with indication of the method and reference to the authors. The mixed Zooplankton has a concentration of 57 ppm Zn/wet wt. which is close to the value of Calanus sp. (41 ppm Zn). The highest concentrations of Zn were obtained in the lamellibranch Crassostrea virginica (1330 - 2-4- ppm/wet wt.) assuming a dry-to-live- weight ratio of 0.2. The relatively low values were observed in Teleostei Merluccius merloccius (15 ppm/wet wt.), Eungraulis mordax (24 ppm/wet wt.)> but Scomber scombrus (155 ppm/wet wt.) and the shark Squalus acantias (420 ppm/wet wt.) had a medium value; the same order of magnitude was found in the Echinoderms (sea-star) -Hymenaster sp. (144 ppm/wet wt.) and the Decapod- Cancer magister (566 ppm/wet wt.)« The amphipods and euphaussiids show low values (14 and 14-30 ppm/wet wt.), respectively.

There have been no direct measurements of stable zinc in phytoplanktonic species in the ocean,, From radiotracer experiments, there is evidence that phytoplankton accumulates zinc in excess of their needs. The cells of marine diatoms Nitzchia caused depletion of zinc from the water after division of ten times.

Accumulation of Zn-65 as shown by autoradiagraphs of small crustaceans, both from food and water, was associated with surfaces of hard and soft tissue.

Euphausia pacifica contained almost 14 times zinc in molted exoskeletons as compared with the element associated with muscle tissue from the same indi- viduals on a live weight basis. The adsorption exchange is the major mechanism for zinc concentration in marine crustaceans. - 112 -

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201-

60 (0 OS IM 100 III

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& BATHYTHERMOGRAPH III 60 a TEMPERATURE-DEPTH PROFILES OF THE CONTINENTAL SHELF.

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rig, 2 1 Data for Bathythermograph Curves i?c-e Table 2 1 100? - Fig. 2

90 In If /

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• /

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i ti ii .< i i i i—+• i i »il ^ 4 6 810* i 4 6 8 10a M DIAMETER - MICRONS

Fig. 2 » 2 Cumulative curves of sediments in the area Atlit - Caesarea. V; ,

,/• 5-19 -•• m • «••»• -• •• • . . . 20-29 - •• •$• '. ' • - • 30-49

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f 03 o. o fUCT« 0.246 s üs 0.212 Ä o *cr* 0.178 e I

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ABSOLUTE FULL ENERGY PEAK EFFICIENCY (%)

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8 3/4 5 » —

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ENERGY (kev) 3.14 Minimim Detectable Total. Activity for Solid Suples 1 1 i

.225 1/4 PARAMETERS:

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/ 1/2 .«25 1 o ///•*•• ' .100

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PARAMETERS: ACCURACY- 20% 7 COUNTING TIME: 5000 min BRANCHING FACTOR- 10 AVERAGE 7 LITERS ce EQUIVALENT PER SAMPLE ui fc 0.4 DENSITY' 130 «/em9 o a

>

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PARAMETERS:

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• >

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ce I I

.01 .02 .05 01 .20 .50 10 2J0 5.0

R- INITIAL PEAK TO BACKGROUND RATIO Figure id? Statistical Accuracy laproveaent Afforded by Low-level Anticoincidence Operation "37 —r —f- 1 1 .60 frXRAT*x i u 8I0TA (88) 8R1SS0P8IS UTRIPERA •n MASS- 333 gram» •oA. a : Él g i? TIME : 1000 nwiurvi n N CONVERSION FACTOR : 1 Mv/chaniMl N CM .40 h RANGE: 0-1000 k«V - »IB S • a S w a m • • * •20 a n a • o m t mV -I 1 § Si« 93 7 A c 8- 1 1 1- 1 1 g S i si 1 0 too 200 300 400 500 600 700 8OO 900 1000

RANGE: 500*1000 luv

M

600 7OO 800 900 1000 ENERGY (k«v>

Figure 3.ÎS Typical Biota Specimen Spectrum: Brissopsis Lyrifera (88) 20

60 120 180 240 300 360 420 Hours

Fig, S..19 Uptake of Zn-65 by Palaemon elegans from filtered sea water performed in March 1970, at constant temperature conditions 250

200

190

& 100 80

60 og 40

20 40 60 80 100 120 140 160 180 200 220 240 Hours

Fig» 3,20 Biological loss of accumulated Zn-65 by Palaemon elegans plotted against time • December 1969 • March 1970 • Ji'iy-August 1970

50 150 ZOO 250 300 350 400 Hours

Fig. 3.21 Uptake of Zn-65 by Palaeaon elagans from filtered sea water in three separate experiments (for explanation see text) L s 100 5 80 60 fac t 40 .2 "o c o o 20 o Poloemon elegans March 1970

20 40 60 80 100 200 400 600 Hours

Fig. 3o22 Concentration factor in Zn-65 in Palaemon elegans. The straight fits the data from two experiments under identical conditions 50 100 150 200 hours

Pig» 4,1 Dots represent, data obtained during experiment. Triangles represent the corrected curve using Chauvenet's criterion. 1 200 hours

Fj.g. 4.2 Concentration factors of Zn-65 in Tapes decussatus Geographical and numerical distribution of apéelos at different depth linen In the Atltt - Ashdod area

K) Fathoms 20-30 Fathoms so Fathoms 100 Fathom» DEPTH SPECIES B D G I As B 0 G lAsBDGIAsBDGI PROFILE 2 4 28 34.3S 46 7 5 27 37 49 10 12 26 38-40 SO 15 2!> 43.44 SI STATIONS ~i 1 1 r Pannatula rubra

Stemaspin sauta ta

Hermodice aarunoulata

»aidant gltbiftx Sabtlla pavenina

Squilln maaeavtmia

ProcVMa aanaliaulata

Ponteoarit oataphraata

Parapênatue UmairowtHë

Netaptnaaua memootrom

Diogtncn pugilator

Dardante arroBor Pagurt8t€0 oaulatua

Pagurue auantntit

Galathta intermedia

Upogebia tipioa

AlphniB glabtr

MaaropipuB depurator

Portunua fuzatatua Maaropodia rostrata

!4Hra fitgax Fil.awuB epiniftr lambrun angulifrma

Ilia nucleus

Inaahuo dorsaltaneio

Ethuta manearon*

Vortppe lanata

Ckarybdie tongiaollis SCALE : [ 100 SPECIMENS

Kumh»r of Hnec*nens per row in Dredge snmnlea ralculated for nunher of tows varying between 1 aod 9 10 Folhoms 20-30 Fottwms so Foihoms ioo Fathom» DEPTH SPECIES BOG IA8BD6 I AS BOG lAtBOGI PROFILE 2 4 28 34.35 46 7 5 27 37 49 10 12 26 38-40 SO 15 23 43.44 81 STATIONS T T" Alaidia Qibba

Area laatea Oonax venus tue

Donax emmistriatu»

Donax tnmauluB Cardiun Çubarautatwt

Cordium pnuaiaoetatum

Haetra oorallina

TtlUna dietorta

Ptoten varita

VtnuB gallina

Glyeimerit piloeue

Dcntalium dental*

Philint nptrta

lumia nualmu

ftuaula ßulaata Sepia offioinalie

íoligo vulgaño

Aporrhaia ptepetieoni

Cerithium recurvum

1+xrex brandaría • Murex trunoulua

ffatiaa flanimtlata Hatioa millepunotata

Satiaa jonephina

Haeea mitabilie

Brisaopais lyrifera Eohinocardium oordatur*

Snhiaaeter aanaliferun

Ophiura texturata

Amphiura chiajoi

Ophiothrix fragilia

AstropBcten pffntaaanthuB 3CM.E: EchinasteT eepositue 1100 SPECIMENS 35« • ...• _,^." ) i

.....''••' y / SCALE: 0 1 2 .y / i

miles .. ••' / / f 50 fa. j / j

> ' j 1 \ \ /f 33» j / /• ICrt)fa. j i / ' • i i V ¡ 9 / 10 / / J ( i : j "i / \ r i / 0- / j ¡ I ! / / J ) HO fa. 6 " r 8 ! J :-. , AKKO i/ 1 ..' /•' r Í ) 2/ // ,••• /•••' / f t) / 3 / 5 i V / } ^Z / / / V : • / s f jf / - s r —•-..-' ¡y J / \ / \ " ' / \ / \ j s. / \ V\ ^y ) i ( / HAIF/!\ i Í

Map I Station Grid in Hai?fa Bay in which Water and Biota Samples Wer¿ Taken / /

/ / / / / / / / 8« //' / ,' 14» horn 7» /; 7 s« m/ «.' 5«

l6f 7 <8* /Co« oreo 23« 229 2!»

/ 25» 27« !**t i 29» 30« Í3!« 32« i'33f Hadara

45* 42«4I» 40«/»38» 37« 36é35«i

i s

8 g ^ /Netaiiya

Map II Grid of Stations off the Israeli Coast in which Benthos Sampling was Carried Out. Map III Sampling Area in the Eastern Mediterranean