DETERMINATION OF NATURAL AND ARTIFICIAL RADIONUCLIDES IN SEA WATER AND SEDIMENTS OFF GWADAR COAST, ARABIAN SEA
Abstract
Determination of naturally occurring radionuclides (226Ra, 228Ra, 40K) and fission fragment (137Cs) in shallow sea water and sediment samples collected from Gwadar coast, Pakistan has been carried out. The activity detected in various sediment samples ranged from 16.9±2.1 to 31.7±3.2 Bq.kg-1 for 226Ra, 9.8±1.2 to 13.3±1.2 Bq.kg-1 for 228Ra and 152.4±11.4 to 244.4±15.7 Bq.kg-1 for 40K. In water samples the activity detected for 40K ranged from 9.3±0.8 to 17.5±3.0 Bq.l-1. The levels of radioactivity for Gwadar area have been compared with the results published in literature for other regions of the world i.e., Irish sea sediment (226Ra = 23.9 Bq.kg-1, 228Ra = 36.7 Bq.kg-1), Pacific Ocean sediments, (226Ra = 21.41.1 Bq.kg-1), Indian Ocean sediment, (226Ra = 13.8 Bq.kg-1, 228Ra= 26.7 Bq.kg-1, 40K = 297.0 Bq.kg-1) and Bay of Bangal (226Ra = 13.9 to 25.2 Bq.kg-1, 40K = 118.3 to 651.9 Bq.kg-1). The level of 40K for Irish sea water is 11.4 Bq.l-1. The mean values of radium equivalent activity, absorbed dose rate and effective dose are 58 Bq.kg-1, 27 nGy.h-1 and 0.03 mSv.y-1 respectively. The value of effective dose is much below the level of 1.0 mSv.y-1, for general public based on stochastic effects recommended by International Commission on Radiological Protection (ICRP). As previously no data on radioactivity of coastal environment of Pakistan is available, the data presented here will serve as baseline for radionuclide concentration in seawater and sea sediments of the study area, and will be included in International Atomic Energy Agency, IAEA’s, Asia Pacific Marine Radioactivity Database (ASPAMARD).References
E. Merril and T. Gesell, Environmental radioactivity: from natural, industrial and military sources, 4th ed. Academic Press, Inc. San Diego (1997).
UNSCEAR, The United Nations Scientific Committee on the Effects of Atomic Radiation, Ionizing Radiation: Sources and Effects, United Nations, New York (1982).
T.E. Myrick; B. A. Berven and F.F. Haywood, Health. Phys. 45 (1983) 31.
F.P.W. Winteringhan, “Radioactive Fallout in Soils, Crops and Food", Food and Agriculture Organization (FAO) of the United Nations, Rome, FAO Soils Bulletin, 61 (1989).
W.L. Templeton and A. Preston., IAEA-SM-72/16 (1966) 267-289.
Y. Nagaya and M. Saiki., J. Radiat. Res. 81 (1967) 37.
V.E. Noshkin, and V.T.Bowen, Concentration and distribution of long lived fallout radionuclides in open ocean sediments. Proceedings of Symposium- Radioactive contamination of the Marine Environment. Seattle, July 1972. IAEA-SM-158/45 (1973) 671-686.
P. McDonald., Radiat. Prot. Dosim., 45, Nos. 1-4, (1992) 707.
P. Strand, and A. L. Rudjord., J. Environ. Radioactivity, 25, Nos. 1-2 (1994) 99.
E. B. Duran., Asia Pacific Marine Radioactivity Database (ASPAMARD), End-of-Mission Report, IAEA/RCA/UNDP Project, RAS/080, Philippine Nuclear Research Institute (1999).
M. Manazul, N, Alam and S.K.S. Hazari., Appl. Radiat. Isot., 51 (1999) 747.
F. Karim Miah., “Regional database on marine radioactivityâ€, Bangladesh country report IAEA/ RCA/UNDP Data Review Meeting, Islamabad, Pakistan, April 12-14 (1999).
IAEA-368, Report on the intercomparison run radionuclides in pacific ocean sediment, International Atomic Energy Agency, IAEA/AL/047 (IAEA/MEL/47), Vienna, Austria, August (1991).
IAEA-135, Report on the intercomparison run, Radionuclides in Irish Sea Sediment,
IAEA/AL/063, International Atomic Energy Agency, Vienna, Austria (1993).
IAEA-315, Report on the intercomparison run, radionuclides in Indian Ocean Sediment, IAEA/AL/065 (IAEA/MEL/61), International Atomic Energy Agency, Vienna, Austria (1996).
M.N. Alam., M.T. Chowdhury, M. Kamal., S. Ghose., N. Mahmmod., M. A. Matin and S.Q. Saikat, Health Physics J. 73, No. 2 (1997) 385.
S. Topcuoglu., D. Kut., N. Esen., N. Gungor., E. Olmez (Egilli) and C. Kirbasoglu., J. Radioanal. Nucl. Chem., 250, No. 2 (2001) 381.
IAEA-381, Report on the intercomparison run, radionuclides in Irish Sea water, IAEA/AL/118 (IAEA/MEL/66), International Atomic Energy Agency, Vienna, Austria (1999).
L. Venturini and M. B. Nisti, Radiat. Prot. Dosim. 71 (1997) 227.
G.E. Adel and Abbady, Appl. Radiat. Isot. 60 (2004) 111.
UNSCEAR, United Nations Scientific Committee on the Effects of Atomic Radiation: Sources and Effects of Ionizing Radiation. Vol. 1. Report to the General Assembly, New York, Annex B (2000).
A. K. Sam and N. Abbas, Radiat. Prot. Dosim. 93, No. 3 (2001) 275.
UNSCEAR, United Nations Scientific Committee on the Effects of Atomic Radiation: Sources and Effects of Ionizing Radiation. Report to the General Assembly, New York (1977).
ICRP-60, Recommendations of the International Commission on Radiological Protection. Pergmon Press, Oxford (1990).