RADIONUCLIDES LEVELS IN MARINE SEDIMENT AND SEAGRASS IN THE NORTHERN GULF OF AQABA, RED SEA

This study investigated the activity concentrations of natural and artificial radionuclides in marine sediment and seagrass form the northern Gulf of Aqaba, aiming at evaluating the radiation levels and their environmental risks. Samples of sediment and seagrass were selected at four representative locations according to human activities in each site. The levels of super(238) U, super(235) U, super(40) K and super(137)Cs were analyzed using Gamma ray spectroscopy techniques, whereas the levels of super(232) Th and super(90) Sr were determined by Inductively Coupled Plasma Mass Spectroscopy (ICP-MS) and beta spectroscopy, respectively. The activity concentrations in sediment for all sites were below detection limit (BDL) - 725.3, BDL - 50.7, BDL - 43.2, and 93.9 - 579.6 Bq kg super(-1) for super(238) U, super(232) Th, super(235) U and super(40) K, respectively. Besides, the activity of super(109) Cd ranged between 12.5 and 588.1 Bq kg super(-1). The results showed that the highest level of radioactivity was at Phosphate Area (PHA) due to anthropogenic activities. The activity concentrations for super(238) U, super(235) U, super(226) Ra, super(232) Th and super(210) Pb in the surface layer of sediment at Phosphate Area (PHA-S) were 725.3, 43.2, 623.2, 50.7 and 430.0 Bq kg super(-1), respectively. On the other hand, the highest concentration of super(40) K in sediment was 579.6 Bq kg super(-1), which was recorded at the surface layer of Marine Science Station site (MSS-S). The highest concentration of super(238) U was detected in seagrass at PHA, which was 253.1Bq kg super(-1). Besides, high levels of super(137) Cs and super(40) K in sea grass were obtained at Tala Bay site as 5.0 and 861.8 Bq kg super(-1), respectively. The calculations of radiation hazard assessment of all investigated sediment samples showed that PHA-S had the highest values. The values of radium equivalent, absorbed dose, annual effective dose, annual gonadal dose, external and internal hazard indices, excess lifetime cancer risk, representative gamma index and activity utilization index at PHA-S were 805.0 Bq kg super(-1), 369.6 nG h super(-1), 0.453 mSv y super(-1), 2.483 mSv y super(-1), 2.176, 4.136, 1.587x10 super(-3), 5.405, and 7.322, respectively.