ABSTRACT
Proceedings of an International Symposium jointly organized by the 'Societe Francaise pour L'Energie Nucleaire' SFEN and 'L'Institut National des Techs. de la Mer' INTECHMER - CNAM at Cherbourg, France, 1-5 June 1987.
TABLE OF CONTENTS
chapter 73|1 pages
10. Vogel, J. S., Southon, J. R., Nelson, D. E. and Brown, T. A., Performance of catalytically condensend carbon for use in accelerator mass spectrometry. Nuclear Instrument and Methods, 1984, 233 289-293. 11. Stuiver, M. and Pollach H. A., Discussion : Reporting of 14C data. Radiocarbon 1977,19 355-363. 12. Stuiver, M. and Ostlund H. G., GEOSECS Indian Ocean and Mediterranean Radiocarbon. Radiocarbon, 1983, 1-19. 13. Broecker, W. S., Peng, T. H., Ostlund, H. G. and Stuiver M., The distribution of bomb radiocarbon in the ocean. I. Geophys. Res., 1985, 90 (C4), 6953-6970. 14 Wunsch, C., An estimate of the upwelling rate in the Equatorial Atlantic based on the distribution of bomb radiocarbon and quasi-geostrophic dynamics. J. Geophys. Res., 1984,
7971-7978. 15. Fine, R. A., Direct evidence using tritium date for throughflow from the Pacific into the Indian Ocean. Nature, 1985, 315, 478480.
chapter 111|1 pages
EFFECT OF NATURAL COLLOIDAL MATTER ON THE EQUILIBRIUM ADSORPTION OF THORIUM IN SEAWATER INTRODUCTION
Sherry E. H. Niven and Robert M. Moore Department of Oceanography Dalhousie University
chapter 114|1 pages
Uncertainties in the results due to ultrafiltration and counting errors are 3% for the particulate fraction and 6% for the dissolved and colloidal fractions. Materials Coastal seawater from Dalhousie University's Aquatron system was photo-oxidized and ultrafiltered (nominal molecular weight cut-off of 1, 000) to prepare batch seawater free of organic material and particles (both colloids and > 0.2 pm). This seawater was used as a control and to prepare samples with specific concentrations of dissolved organic matter (DOM), colloids, and particles. Th was prepared by extraction from uranyl nitrate using a procedure based on
as a quench monitor. The activity of the 234Th quench standard was determined to 1.6% accuracy by counting its 63 and 93 KeV 7-rays on a Ge(Li)-detector calibrated with Amersham Mixed Standard 1000. Background for the liquid scintillation counter was 38 cpm. Exudates from batch cultures of the diatom as dissolved (< 1, 000 NMW) organic matter in the experiments.
chapter 116|1 pages
100 -H1 (a) Thp 80 H _c 60 0 ..9 40 20 12345 Alumina Concentration (mg/I) 100 (b) 80 Thd 60 I0 -
2 3 Alumina Concentration (mg/I)
chapter 127|50 pages
Mass 4Th _700 dpm.m -. 2 d -1 300 — _ 500250 — 1 -300 \ 200 - 100 50 — 3000 _ 2000 034Th
Flux 1 2 3 4 5 6 1 2 3 4 5 1 2 3 % 6 0 0 1 0 0 0
chapter 223|1 pages
Local spatial heterogeneity, both horizontal and vertical, is accompanied by daily temporal variations which we detected at sampling point 5. Between 28.08.86 and 03.09.86, the 137Cs concentration of the surface waters, under the permanent influence of Rhone deposits, fluctuated between 4 and 24 mBq/1 (Figure 4). This spread of values reflects both the variations in deposits over the period of time in question and the variable rates at which freshwater and seawater mix. The Golfe du Lion In September 1986, levels of 137Cs in the surface waters of the continental shelf of the Golfe du Lion varied from 1.5 to 6.5 mBq/1 with an average of 3.0 mBq/1 and a 137Cs/ 134Cs between 2.5 to 5.0. These figures were much lower than those obtained at sampling points at the eastern boundary of the gulf, on average 12 mBq/1 (4.5 mBq/1 of 134Cs), but slightly higher than those at the southern boundary which were equal to 2.5 mBq/1 (1.0 mBq/1 of 134Cs) on average (Figure 5A). The decreasing spatial gradient from east to west seems to correspond to a stock of cesium carried by waters in the Ligurian-Provenal geostrophic current coming from the north-west Mediterranean basin. The absence of major rainfall prior to the dates of the sampling definitely restricted the amount of soil washed away into the Rhone and thus the quantity of 137 Cs the latter was carrying. The levels recorded in the Gulf must therefore have been chiefly due to direct atmospheric fallout onto the surface waters in the eastern part of the north-west basin. At the time of the sampling operation in December 1986 (Figure 5B), the mean 137Cs and 134Cs activities of the surface waters of the continental shelf were higher: 7.0 mBq/1, for activity levels between 6.0 and 8.0 mBq/1 of 137Cs and 1.0 to 2.5 mBq/1 for 134Cs. A central strip running from north east to south west, joining the Rhone delta to the Cote Vermeil, had the highest 137 Cs readings which were constantly in the region of 8.0 mBq/1 (Figure 5B). These findings are to be compared with those of ALAIN (6), MINAS (7) and TOURNIER (8). The higher volume of deposits in the waters of the Rhone after the autumn rains and the increase of low level industrial releases made it possible to track the Rh6ne water across the gulf. Sampling points at the east and south boundaries of the continental layer of surface water characterised by high 137Cs levels and appearance of 134 Cs reflects the gradual spread of these elements towards the sea bed.
lf recorded the lowest values, between 2 and 6 mBq/1 of As regards sampling points on the Golfe du Lion continental shelf, the vertical distribution of 137Cs and 134Cs readings gave the highest values from the surface to a depth of 70 m in September 1986 and to a depth of 200 m in December 1986. The increase over a period of time in the depth of the
chapter 230|1 pages
U
activity concentration NORTH BEA —FS "Borkumrifr NORTH SEA ----FS "Elbe 1" BALTIC SEA—.—FS "Fehmarnbelt"
chapter 231|2 pages
oceanographic measurements. In the southern part of the North Sea the mixed layer reached down to the sea floor and in the northern part of the North Sea down to a depth of 40 to 60 meters. In the vicinity of the south Norwegian coast a thickness of 100 meters can be assessed. Proceeding from that, one can calculate the radioactive inventory of the surface layer areally and represent it as areal deposition. Fig. 6 shows the Cs 137 distribution pattern of the Chernobyl Fallout deposition in kBq/ms resulting from the mean radionuclide ratio Cs134/Cs137. Ostsee SchleimOndung
1986 I 1987 Fig. 3 The Cs 137 and Sr 90 surface activity concentration at the position Schleimiinde in the western Baltic Sea
chapter 303|5 pages
239,240pu H/S = 0.024. The annual mean discharges in 1980-81 from Sellafield (BNFL 1979-1986)[ 3] were: 31 TBq 99 Tc, 0.76 TBq 60 Co, and 17.5 TBq 239,240 Pu. We would thus predict the annual mean discharges from La Hague in 1983-84 to 9 TBq 99 Tc, 2.5 TBq 60Co, and 0.4 TBq 239,240 Pu. We have no complete data from 1983-84 from La Hague, but for 1983 Patti et al. (1984)[11] re-ported 11.7 TBq 99 Tc and for 1982 Calmet & Guegeniat (1985)[4] reported annual discharges of 3.1 TBq "Co and 0.12 TBq 239,240 Pu. If we assume that the discharges from La Hague in the later years were relatively constant, we may conclude that the above estimates from Fucus measurements seem reason-able. CONCLUSION The radionuclide concentrations in seaweed along the continen-tal side of the English Channel are inversely proportional to the distance (in km) or square root of the distance from La Hague. Similar distance relations have been observed earlier in British coastal water for liquid discharges from Sellafield These relations may be applied for estimates of the annual discharges from the reprocessing plants in Western Europe. REFERENCES 1. Aarkrog A., Dahlgaard H., Hallstadius L., Hansen H. and Holm E. (1983). Nature 304, 49-51. 2. Aarkrog A. et al. (1983-1985). Risen Reports, Nos. 488, 509, 510, 527 and 528. Rises National Laboratory, Roskilde, Denmark. 3. BNFL (1979-1986). Annual report on radioactive discharges and monitoring of the environment 1978-1985. British Nuclear Fuels Limited, Warrington, Cheshire, U.K. 4. Calmet D. & Guegueniat P. (1985), in: IAEA-TECDOC-329 pp. 111-144 International Atomic Energy Agency, Vienna. 5. Casso S.A. & Livingson H.D. (1984). WHO-84-40. Woods Hole Oceanographic Inst. 6. Harley J.H. (editor) (1972). HASL-300. Environmental measurements Laboratory, New York. 7. Holm E., Rioseco J., & Garcia-Leon M. (1984). Nucl. Instr. and Meth. in Phys. Res. 223, 204-207. 8. Jefferies D.F., Steele A.K. and Preston A. (1982). Deep-Sea Res. 29, 713-738. 9. Kautsky H. (1973). Deutschen Hydrographischen Zeitshrift, 26, 242-246. Livingston
H.D., Bowen V.T. & Kupferman S.L. (1982). J. mar. Res. 40, 1227-1258. Patti F., Masson M., Vergnaud G. & Jeanmaire L. (1984), in: Technetium in the Environment (Desmet G & Myttenaere C. editors) pp. 37-51. Elsevier Applied Science Publishers, London & New York.
chapter 358|2 pages
Table 2. The 241 239/240 Pu activity ratio for different chemical fractions in surface sediment (0-3 cm) collected in 1968 and 1984. 241Am/239+240 Pu activity ratio Fraction 1968 1984 Exchangeable 0.20 + 0.04 1.21 + 0.30 Bound to carbonates 1.43 T 0.09 1.13 T 0.10 T 0.02 T 0.23 T
Bound to Fe/Mn oxides 0.28 + 0.08 0.20 Bound to organic matter-sulfides 0.28 0.12 + 0.05 Residual 0.026 + 0.001 0.10 0.03 weighted mean 0.040 + 0.007 0.098+ 0.005 (6;18) (n=29)